found this list in ebay guides. i am going to elaborate on it by adding more first appearances. tell me some characters and their first appearances. if there is a mistake please correct me.Absorbing Man - Journey Into Mystery #114 (1965)
Adam Strange - Showcase #17 (1958)
Agatha Harkness - Fantastic Four #94
Alfred - Batman #16 (1943)
Alpha Flight - X-men #120 & X-men #121 (1979)
Amazing man- Amazing-man #5
Amazo - Brave and the Bold #30 (1960)
Angel - X-men #1 (1963)
Animal Man - Strange Adventures #180 (1965)
Antman - Tales to Astonish #27 (1962) #35 (1st in Costume) (1962)
Aquaman - More Fun Comics #73 (1941)
Archangel - cameo X-Factor #23, 1st Full Appearance X-Factor #24
Archie - Pep Comics #22 (1941)
Aries - Thor #129 (1966)
Arion - Warlord #55
Avengers - Avengers #1 (1963)
Banshee - X-men #28 (1967)
Bat Lash - Showcase #76 (1968)
Batgirl - Detective Comics #359 (1967)
Batman - Detective Comics #27 (1939)
Batroc - Tales of Suspense #76
Batwoman - Detective Comics #233 (1956)
Beast - X-men #1 (1963)
Beast (Blue) - Amazing Adventures #11
Betty - Pep Comics #22 (1941)
Beyonder - Secret Wars #1 (1984)
Bizarro - Superboy #68 (1958)
Black Adam (Fawcett/DC) - Marvel Family #1 (1945)
Black Bolt - cameo Fantastic Four #45 1st Full App. Fantastic Four #46 (1965-66)
Black Canary - Flash Comics #86 (1947)
Black Cat - Amazing Spiderman #194 (1979)
Black Knight - Tales to Astonish #52 (1964)
Black Panther - Fantastic Four #52 (1966)
Black Terror - Exciting Comics #9 (1941)
Black Widow - Tales of Suspense #52 (1964)
Blade - Tomb of Dracula #10 (1973)
Blob - X-men #3 (1964)
Blue Beetle - Mystery Men #1 (1940) Silver Age, Blue Beetle #18 (1955) as Ted Kord, Captain Atom #83 (1966)
Boomerang - Tales to Astonish #81 (1966)
Booster Gold - Booster Gold #1 (1986)
Brainiac - Action Comics #242 (1958)
Brotherhood of Evil Mutants - X-men #4 (1964)
Buck Rogers - Famous Funnies #3 (1934)
Buffy the Vampire Slayer - Dark Horse Presents Annual 1998
Bugs Bunny - Looney Tunes #1 (1941)
Bullseye - Nick Fury, Agent of Shield #15 (1969)
Bullseye II - Daredevil #131 (1976)
Cable - as baby Uncanny X-men #201 (1986) 1st full app New Mutants #87 (1990)
Canonball - Marvel Graphic Novel #4
Captain America - Captain America Comics #1 (1941) Silver Age app. Avengers #4 (1964)
Captain Atom (Charlton/DC)- Space Adventures #33 (1960)
Captain Boomerang - The Flash #117 (1961)
Captain Marvel (Fawcett/DC) - Whiz Comics #1 (1940)
Captain Marvel Jr. (Fawcett/DC) - Whiz Comics #25 (1941)
Captain Marvel (Marvel) - Marvel Super Heores #12 (1967)
Captain Marvel (Marvel/Female) - Amazing Spiderman Annual #16 (1982)
Captain Triumph - Crack Comics #27 (1943)
Carnage - Amazing Spiderman #344 & 345 (Cameo) #361 (1st Full App.) (1993)
Cat (later becomes Tigra) - The Cat #1 (1972)
Catwoman - as Cat Batman #1 (1940) 1st Full App. as Catwoman in Costume Batman #3 (1940)
Cerebus - Cerebus #1 (1977)
Challengers of the Unknown - Showcase #6 (1957)
Chameleon - Amazing Spiderman #1 (1963)
Champions - The Champions #1 (1975)
Checkmate - Action Comics #598 (1988)
Cloak & Dagger - Spectacular Spiderman #64 (1982)
Colossus - Giant Size X-men #1 (1975)
Conan - Conan the Barbarian #1 (1970)
Concrete - Dark Horse Presents #1 (1986)
Constantine (Hellblazer) - Saga of the Swamp Thing #25 (Cameo) #37 (1st Full App.)
Creeper - Showcase #73 (1968)
The Crow (movie) - Caliber Presents #1 (1989)
Cyclops - X-men #1 (1963)
Daffy Duck - Looney Tunes #1 (1941)
Daredevil (Gleason Pub.) - Silver Streak Comics #6 (1940)
Daredevil (Marvel) - Daredevil #1 (1964)
Darkhawk - Darkhawk #1 (1991)
Darkseid - Superman's Pal Jimmy Olsen #134 (1970)
Dazzler - X-men #130 (1980)
Deadman - Strange Adventures #205 (1967)
Deathlok - Astonishing Tales #25 (1974)
Deathstroke - New Teen Titans #2 (1980)
Defenders - Marvel Feature #1 (1971)
Dennis the Menace - Dennis the Menace #1 (1953)
Dick Tracy - Popular Comics #1 (1936)
Doctor Doom - Fantastic Four #5 (1962)
Doctor Fate - More Fun Comics #55 (1940)
Doctor Light - Justice League of America #12 (1962)
Doctor Strange - Strange Tales #110 (1963)
Doc Octopus - Amazing Spiderman #3 (1963)
Doll Man - Feature Comics #27 (1939)
Don Winslow - Popular Comics #1 (1936)
Doomsday - Cameo Superman: The Man of Steel #17 1st Full App. Superman: The Man of Steel #18 (1993)
Electro - Amazing Spiderman #9 (1964)
Elektra - Daredevil #168 (1980)
Elmer Fudd - Looney Tunes #1 (1941)
Elongated Man - The Flash #112 (1960)
Enemy Ace - Our Army at War #151 (1965)
Eternals - Eternals #1 (1976)
Evil Ernie - Evil Ernie #1 (1991)
Fantastic Four - Fantastic Four #1 (1961)
Fighting American - Fighting American #1 (1954)
Fighting Yank - Startling Comics #10 (1941)
Firestorm - Firestorm #1 (1978)
Flame - Wonderworld Comics #3 (1939)
Flaming Carrot - Flaming Carrot Comics #1 (1981)
Flash (DC) - Flash Comics #1 (1940) Silver Age app. Showcase #4 (1956)
Flash Gordon - King Comics #1 (1936)
Frankie Raye - Fantastic Four #164 (1974)
Franklin Richards - Fantastic Four Special #6 (1968)
Galactus - cameo Fantastic Four #48 1st Full App. Fantastic Four #49 (1966)
Gambit - Cameo X-men Annual 14 (1990) 1st Full App. X-men #266 (1990)
Gen13 - Deathmate: Black (1993)
Ghost Rider - Marvel Spotlight #5 (1972)
Giant Man - previously Ant Man, Tales to Astonish #49 (1963)
Gorgon - Fantastic Four #44 (1965)
Green Arrow - More Fun Comics #73 (1941)
Green Goblin - Amazing Spiderman #14 (1964)
Green Hornet - Green Hornet Comics #1 (1940)
Green Lantern (Original) - All American Comics #16 (1940)
Green Lantern (Hal Jordan) - Showcase #22 (1959)
Green Lantern (Kyle Rayner) - Green Lantern #48 (1994)
Grendel - Primer #2 (1982)
Guardians of the Galaxy - Marvel Super Heroes #18 (1969)
Guy Gardner - Green Lantern #59 (1968)
Havok - w/o Costume X-men #56 (1969) 1st Full app.X-men #58 (1969)
Hawk & Dove - Showcase #75 (1968)
Hawkeye - Tales of Suspense #57 (1964)
Hawkgirl - All Star Comis #5 (1941)
Hawkman - Flash Comics #1 (1940)
He-Man - DC Comics Presents #47 (1982)
Hector Hammond - Green Lantern Vol. 2 #5 (1961)
Hellboy - ,San Diego Comic Con Comics #2 (1993) in color Next Men #21
Hercules - Journey Into Mystery Annual #1 (1965)
High Evolutionary - Thor #134 (1966)
Hobgoblin - Amazing Spiderman #238 (1983)
Howard The Duck - Adventures Into Fear #19
Hulk - Incredible Hulk #1 (1962)
Human Torch - Marvel Comics #1 (1939) Silver Age app. Fantastic Four #1 (1961)
Iceman - X-men #1 (1963)
Impulse - Flash Vol. 2 #92 (1994)
Infinity, Inc. - All Star Squadron #25 (1983)
Inhumans - Fantastic Four #45 (1965)
Invaders - Avengers #71 (1969)
Invincible - Noble Causes: Family Secrets #3 (2002)
Invisible Woman - Fantastic Four #1 (1961)
Ion (Kyle Rayner) - Green Lantern #145
Iron Fist - Marvel Premiere #15 (1974)
Iron Man - Tales of Suspense #39 (1963)
Jigsaw - Amazing Spiderman #162 (1976)
Jimmy Olsen - Action Comics #6 (1938)
John Stewart (Green Lantern) - Green Lantern #87 (1972)
Johnny Quick - More Fun Comics #71 (1941)
Johnny Thunder - Flash Comics #1 (1940)
Jonah Hex - All Star Western #10 (1972)
Joker - Batman #1 (1940)
Jonny Quest - Jonny Quest #1 (1964)
Jubilee - X-men #244 (1989)
Juggernaut - X-men #12 (1965)
Jughead - Pep Comics #22 (1941)
Justice League of America - Brave & the Bold #28 (1960)
Justice Society of America - All Star Comics #3 (1940)
Kamandi, The Last Boy on Earth - Kamandi #1 (1972)
Kandor City - Action Comics #242 (1958)
Karma- Marvel Graphic Novel #4
Kato - Green Hornet Comics #1 (1940)
Kazar - Marvel Comics #1 (1939) Silver Age App. X-men #10 (1964)
Killraven - Amazing Adventures #18 (1973)
Kingpin - Amazing Spiderman #50 (1967)
Kitty Pryde - X-men #129 (1980)
Kraven the Hunter - Amazing Spiderman #15 (1964)
Kull the Conqueror - cameo Conan #1 (1970) 1st Full App. Creatures on the Loose #10 and Kull the Conqueror #1 (1971)
Lady Death - Evil Ernie #1 (1991)
Lady Deathstrike - Alpha Flight #33 (1986)
Leader - Tales to Astonish #62 (1965)
Legion of Super Heroes - Adventure Comics #247 (1958)
Lex Luthor - Action Comics #23 (1940)
Lizard - Amazing Spiderman #6 (1963)
Lobo - Omega Men #3 (1983)
Loki - Journey Into Mystery #85 (1962)
Luke Cage - Hero for Hire, Luke Cage #1 (1972)
Mad Hatter - Detective Comics #230 (1956)
Magneto - X-men #1 (1963)
Man-Bat - Detective Comics #400 (1970)
Man-Thing - Savage Tales #1 (1971)
Martian Manhunter - Detective Comics #225 (1955)
Marvel Girl (Jean Grey) - X-men #1 (1963)
Marvel Zombies - Ultimate Fantastic Four #21
Mary Jane Watson - Amazing Spiderman #25 (1965)
Mask (movie) - Dark Horse Presents #10 (1987)
Mephisto - Silver Surfer Vol. 1 #3 (1968)
Metal Men - Showcase #37 (1962)
Metamorpho - Brave & the Bold #57 (1964)
Mickey Mouse - Mickey Mouse Book No# (1930)
Mimic - X-men #19 (1966)
Miracleman - Miracleman #1 (1985) as Marvelman (Marvelman #25 in 1954)
Mirror Master - The Flash #105 (1959)
Mister Miracle - Mister Miracle #1 (1971)
Mister Sinister - X-men #221 (1989)
Modok - Tales of Suspense #94 (1967)
Molecule Man - Fantastic Four #20 (1963)
Mole Man - Fantastic Four #1 (1961)
Moon Knight - Werewolf By Night #32 (1975)
Moonstar- Marvel Graphic Novel #4
Morbius - Amazing Spiderman #101 (1971)
Mouse Guard - Mouse Guard The Dark Ghost #1 (2006)
Ms. Marvel (Marvel) - as Carol Danvers Marvel Super Heroes #13 (1967) as hero Ms. Marvel #1 (1977)
Mxyztplk - Superman #30 (1944)
Mysterio - Amazing Spiderman #13 (1964)
Mystery Men (movie) - Flaming Carrot #16 (1987)
Mystique - Ms. Marvel #16 & #17 (Cameo) #18 (1st Full App.) (1978)
New Mutants - Marvel Graphic Novel #4 (1982)
New Warriors - Thor #411 (Cameo) #412 (1st Full App.)
Next Men - Dark Horse Presents #54 (1991)
Nightcrawler - Giant Size X-men #1 (1975)
Nightwing (Dick Grayson) - Tales of the Teen Titans #44 (1984)
Nitro - Captain Marvel #34 (1974)
Nth Man - Marvel Comics Presents #25 (1989)
Nuke - Daredevil #232 (1985)
Odin - Journey Into Mystery #86
O.M.A.C. - O.M.A.C. #1 (1974)
Omega The Unknown - Omega The Unknown #1 (1976)
Orion - The New Gods #1 (1971)
Penguin - Detective Comics #58 (1941)
Phantom - Ace Comics #11 (1938)
Plastic Man - Police Comics #1 (1941)
Pogo the Possum - Animal Comics #1 (1941)
Porky Pig - Looney Tunes #1 (1941)
Power Girl - All Star Comics #58 (1976)
Preacher - Preacher #1 (1995)
Prime - Prime #1 (1993)
Prince Valiant - Ace Comics #26 (1939)
Professor X - X-men #1 (1963)
Puma - Amazing Spiderman #256 (1984)
Punisher (Marvel) - Amazing Spiderman #129 (1974)
Question - Captain Atom #83 (1966)
Quicksilver - X-men #4 (1964)
Ra's al Ghul - Batman #232 (1971)
Ragman - Ragman #1 (1976)
Red Ryder - Crackajack Funnies #9 (1939)
Reed Richards - Fantastic Four #1 (1961)
Red Wolf - Avengers #80 (1970)
Rhino - Amazing Spiderman #41 (1966)
Riddler - Detective Comics #140 (1948) Silver Age App. Batman #171 (1965)
Rip Hunter - Showcase #20 (1959)
Robin I (Dick Grayson) - Detective Comics #38 (1940)
Robin II (Jason Todd) - as Jason Todd Batman #357 (1983) as Robin unofficially Batman #366-367 Officially Batman #368 (1984) "Death" Batman #428 (1988)
Robin III (Tim Drake) - as Timothy Drake Batman #436 (1989) as Robin Unofficially Batman #442 Officially Batman #457 (1991)
Rocketeer - Cameo Starslayer #1 1st Full App. #2 (1982)
Rogue - Avengers Annual #10 (1981)
Rom - Rom #1 (1979)
Sabretooth - Iron Fist #14 (1977)
Saint of Killers - Preacher #2 (1995)
Sandman - Amazing Spiderman #4 (1963)
Savage Dragon - cameo Megaton #2 1st Full App. Megaton #3 (1985)
Scalphunter - Weird Western Tales #39
Scarecrow - World's Finest Comics #3 (1941)
Scarlet Witch - X-men #4 (1964)
Sentinels - X-men #14 (1965)
Sentry - Sentry #1 (2000)
Sgt. Fury - Sgt. Fury & His Howling Commandos #1 (1963)
Sgt. Rock - cameo Our Army at War #81-82 1st Full App. #83 (1959)
Sharon Carter, Agent 13 - As Agent 13, Tales of Suspense #75 As Sharon Carter, Tales of Suspense #76
Sheena, Queen of the Jungle - Jumbo Comics #1 (1938)
She-Hulk - Savage She-Hulk #1 (1980)
Silver Sable - Amazing Spiderman #265 (1985)
Silver Surfer - Fantastic Four #48 (1966)
Sinestro - Green Lantern #7 (1961)
Son of Satan - cameo Ghost Rider #1 (1973) 1st Full app. Ghost Rider #2 (1973)
Spawn - Spawn #1 (1992)
Spectre - cameo More Fun Comics #51 1st Full App. More Fun Comics #52 (1940)
Speedball - Amazing Spiderman Annual #22 (1988)
Spiderman - Amazing Fantasy #15 (1962)
Spider Girl - What If? Vol.2 #105 (1998)
Spider Woman - Marvel Spotlight #32 (1977)
Spirit - Police Comics #11 (1942)
Squadron Sumpreme - as Squadron Sinister Avengers #70 (1969)
Steel (The Indestructable Man) - Steel #1 (1978)
Storm (Marvel) - Giant Size X-men #1 (1975)
Sub-Mariner - Marvel Comics #1 (1939)
Suicide Squad - Brave & the Bold #25 (1959)
Sunfire - X-men #64 (1970)
Sunspot- Marvel Graphic Novel #4
Superboy - More Fun Comics #101 (1945)
Superboy Prime - DC Comics Presents #87 (1985)
Supergirl - Action Comics #252 (1959)
Superman - Action Comics #1 (1938)
Supernova (DC) - World's Finest Comics #178 (1968)
Super Patriot - Nick Fury Agnet of Shield #13 (1969)
Superwoman - DC Comics Presents Annual #2 (1983)
Supreme - Youngblood #3 (1992)
Swamp Thing - House of Secrets #92 (1971)
Talia (Ra's al Ghul's Daughter) - Detective Comics #411 (1971)
Tarzan - Tip Top Comics #1 (1936)
Taskmaster - Avengers #195 (Cameo) #196 (1st Full App.) (1980)
Teen Titans - Brave & the Bold #54 (1964)
Teenage Mutant Ninja Turtles - Ad cameo Gobbledygook #1 1st Full App. Teenage Mutant Ninja Turtles #1 (1984)
Terry & The Pirates - Popular Comics #1 (1936)
Thanos - Iron Man #55 (Cameo) (1973)
Thing - Fantastic Four #1 (1961)
Thor - Journey Into Mystery #83 (1962)
Thunderbird - Giant Size X-Men #1 (1975)
Thunderbolts - Incredible Hulk #449 (1997)
Thunderstrike - Thor #459 (1993)
Tick - The Tick Special Edition #1 (1988)
Tigra (formerly The Cat) - Giant Size Creatures #1 (1974)
Toad - X-men #4 (1964)
Tom & Jerry - Our Gang Comics #1 (1942)
Tomahawk - Star Spangled Comics #69 (1947)
Transformers - Transformers #1 (1984)
Two Face - Detective Comics #66 (1942) Silver Age App. Batman #234 (1971)
Two Gun Kid - Wild West #1 (1948)
Uncle Scrooge McDuck - Four Color #178 (1947)
Underdog - Underdog #1 (1970)
Union Jack I - Invaders #7 (1976)
Union Jack II - Invaders #20 (1977)
Union Jack III - Captain America #254 (1981)
Unknown Soldier - Our Army At War #168 (1968)
U.S. Agent - Captain America #354 (1989)
Usagi Yojimbo - Albedo #2 (1984)
Vampirella - Vampirella #1 (1969)
Vault Keeper - War Against Crime #10 (1949)
Venom - Web of Spiderman #18 (behind the scenes) & Amazing Spiderman #298-299 (Cameo) #300 (1st Full Appearance) (1988)
Veronica - Pep Comics #26 (1942)
Vigilante - Action Comics #42 (1941) Silver Age, Justice League of America #78 (1970)
Vixen - Action Comics #521 (1981)
Vulture - Amazing Spiderman #2 (1963)
Warlock - Fantastic Four #66 & 67 (1968)
Warlord - First Issue Special #8 (1975)
War Machine - cameo Iron Man #281 1st Full App. Iron Man #282 (1992)
Warpath - New Mutants #16 (1984)
Wasp - Tales to Astonish #44 (1963)
Watchmen - Watchmen #1 (1986)
Wendigo - Incredible Hulk #162 (1973)
Werewolf By Night - Marvel Spotlight #2 (1972)
White Queen (Emma Frost) - X-men #129 (1980)
Wolfsbane- Marvel Graphic Novel #4
Wolverine - Incredible Hulk #180 (Cameo) #181 (1st Full Apearance) (1974)
Wonder Man - Avengers #9 (1964)
Wonder Woman - All Star Comics #8 (1941)
X - Dark Horse Comics #8 (1993)
X-23 - NYX #3 (2003)
X-Factor - Avengers #263 (1986)
X-Man (Nate Grey) - X-Man #1 (1995)
X-men - X-men #1 (1963)
X-O Manowar - 1st App. of X-O Armor, Magnus #7 (1991-92) Aric X-O Manowar 1st App, X-O Manowar #1 (1992)
Yorick Brown - Y: The Last Man #1 (2002)
Youngblood - Megaton Explosion (1987)
Zatanna - Hawkman #4 (1964)
Zorro - Zorro Four Color #228 (1949)