you're right, and wrong. He's appeared in 27 Movies according to IMDB

# The Incredible Hulk (2008) (uncredited)
# 4: Rise of the Silver Surfer (2007) .... Rejected Wedding Guest
... aka Fantastic Four: Rise of the Silver Surfer (Germany) (USA: promotional title)
# Spider-Man 3 (2007) .... Man in Times Square
... aka Spider-Man 3: The IMAX Experience (USA: IMAX version)
# The Condor (2007) (V) (voice) .... Grandfather
... aka Stan Lee Presents: The Condor (USA: DVD box title)
# "Heroes" .... Bus Driver (1 episode, 2007)
... aka Heroes: Villains (USA: promotional title)
- Chapter Sixteen 'Unexpected' (2007) TV episode .... Bus Driver
# Mosaic (2007) (V) (uncredited) .... Stanley
... aka Stan Lee Presents Mosaic (USA: DVD box title)
# X-Men: The Last Stand (2006) .... Waterhose Man
... aka X-Men 3 (Singapore: English title) (USA: working title)
... aka X3 (International: English title: informal short title) (USA: promotional abbreviation)
# Fantastic Four (2005) .... Willie Lumpkin
... aka Fantastic Four (Germany)
# The Princess Diaries 2: Royal Engagement (2004) .... Three Stooges Wedding Guest
# Spider-Man 2 (2004) .... Man Dodging Debris
... aka Spider-Man 2.1 (USA: recut version)
... aka Spider-Man 2: The IMAX Experience (USA: IMAX version)
# "Spider-Man" .... Frank Elson (1 episode, 2003)
... aka Spider-Man: The New Animated Series (Canada: English title: DVD box title) (USA: DVD box title)
- Mind Games: Part 1 (2003) TV episode (voice) .... Frank Elson
# Hulk (2003) .... Security Guard
# Daredevil (2003) .... Old Man at Crossing
... aka Daredevil: A Daring New Vision (USA: director's cut (DVD title))
# Parts of the Family (2003) (V) .... Proffesor Peter Parker, Film Critic
# Spider-Man (2002) (uncredited) (unconfirmed) .... Man in Fair
# Citizen Toxie: The Toxic Avenger IV (2000) (voice) (as Peter Parker) .... Prologue/Epilogue Narrator
# Spider-Man (2000) (VG) (voice) .... Narrator
# X-Men (2000) .... Hot Dog Vendor
... aka X-Men 1.5 (USA: DVD box title)
# The Adventures of Cinderella's Da

cont...

# The Adventures of Cinderella's Daughter (2000) .... The Priest
# "The Seventh Portal" (2000) TV series (voice) .... Izayus

# "Spider-Man" .... Stan 'the Man' Lee (1 episode, 1998)
- Spider Wars, Chapter 2: Farewell Spider-Man (1998) TV episode (voice) .... Stan 'the Man' Lee
# "The Incredible Hulk" .... Cliff Walters (1 episode, 1997)
- Down Memory Lane (1997) TV episode (voice) .... Cliff Walters
# The Ambulance (1990) .... Marvel Comics Editor

# The Trial of the Incredible Hulk (1989) (TV) (uncredited) .... Jury Foreman
# "Spider-Man and His Amazing Friends" .... Narrator (14 episodes, 1981-1982)
- A Firestar Is Born (1982) TV episode (voice) .... Narrator
- Quest of the Red Skull (1981) TV episode (voice) .... Narrator
- Pawns of the Kingpin (1981) TV episode (voice) .... Narrator
- Knights & Demons (1981) TV episode (voice) .... Narrator
- The Vengeance of Loki (1981) TV episode (voice) .... Narrator
(9 more)
# "The Incredible Hulk" (1982) TV series .... Narrator (unknown episodes)
... aka The All New Incredible Hulk (UK: video box title)

# An 01, L' (1973) (voice) .... Récitant/New York's Narrator
... aka The Year 01 (International: English title)

I stand corrected. 21 Movies, not 27. You're still wrong.

Since you seem to be this interested in it, first of all, why don't you get an account? & secondly, check out This Article - which includes a YouTube video of some of his Marvel appearances, and a pretty funny interview!

which, btw, he talks about his Cameo in Ironman, which happens to not be on this list & you claim didn't happen.