Stan Lee
Is there a more iconic cameo than Stan Lee himself? He's appeared in Spiderman: Homecoming as an angry neighbor, a drunken war veteran in Avengers: Age of Ultron, an elderly barber in Thor: Ragnarok, and a classical music listener in The Amazing Spiderman. He plays a Hugh Hefner lookalike in Iron Man, a bus commuter in Doctor Strange, and an interrupted citizen in Guardians of the Galaxy Volume 2.