Information taken from this site: Comic Vine ( comicvine.com )

DC Comics characters link: https://comicvine.gamespot.com/dc-comics/4010-10/characters/

Shortcut: https://comicvine.gamespot.com/dc-comics/4010-10/characters/

Marvel Comics characters link: https://comicvine.gamespot.com/marvel/4010-31/characters/

Shortcut: https://comicvine.gamespot.com/marvel/4010-31/characters/

Publisher: Character (First Appearance) - Number of Appearances

#1 DC: Batman (1939) - 15781 appearances

#2 DC: Superman (1938) - 14195 appearances

#3 Marvel: Wolverine (1974) - 13285 appearances

#4 Marvel: Spider-Man (1962) - 12546 appearances

#5 Marvel: Captain America (1940) - 9444 appearances

#6 Marvel: Cyclops (1963) - 9202 appearances

#7 Marvel: Iron Man (1963) - 8988 appearances

#8 Marvel: Ororo Munroe aka Storm (1975) - 8051 appearances

#9Marvel: Beast (1963) - 7941 appearances

#10 Marvel: Thing (1961) - 6667 appearances

#11 Marvel: Thor (1962) - 6582 appearances

#12 DC: Dick Grayson (1940) - 6473 appearances

#13 Marvel: Iceman (1963) - 6457 appearances

#14 Marvel: Hulk (1962) - 6292 appearances

#15 DC: Wonder Woman (1941) - 6239 appearances

#16 Marvel: Colossus (1975) - 6204 appearances

#17 Marvel: Jean Grey (1963) - 6181 appearances

#18 Marvel: Professor X (1963) - 6122 appearances

#19 Marvel: Angel (1963) - 6114 appearances

#20 Marvel: Mr. Fantastic (1961) - 5717 appearances

#21 Marvel: Human Torch (1961) - 5686 appearances

#22 Marvel: Nightcrawler (1975) - 5631 appearances

#23 Marvel: Rogue (1981) - 5392 appearances

#24 Marvel: Invisible Woman (1961) - 5187 appearances

#25 Marvel: Kitty Pryde (1980) - 5059 appearances

Thor / Spider-man / Captain America / Hulk / Iron Man