You know, like Kevin Costner played Jim Garrison in JFK and Jim Garrison himself played Earl Warren in the same film.
Well, I saw a tremendous new British independent film last night called Telstar, the sad but true story of a noted 60s British record producer who famously turned down the chance to produce The Beatles but also produced the first ever record by a British group to top the US charts (the eponymous Telstar by The Tornados). The film featured at least four people who were also portrayed as characters. Thus:
Chas Hodges - played by Ralf Little and appeared as a disgruntled neighbour
Clem Cattini - played by James Cordon and appeared as a chauffeur
Jess Conrad - played by Nigel Harman but appeared as “Larry Parnes”
and, best of all
John Leyton - played by Callum Dixon but appeared as the bloke awarding a gold disc to Joe Meek and John Leyton (i.e. his 1961 self) for his number 1 hit “Johnny Remember Me”.
Chuck Yeager appears in The Right Stuff as a bartender at Pancho’s. He’s portrayed in the movie by Sam Shepard.
Jim Lovell appears in Apollo 13 as the captain of the aircraft carrier that retrieves the astronauts after splashdown. He’s portrayed in the movie by Tom Hanks.
Archival footage may be a bit of a cheat, but in Chaplin, Robert Downey Jr. as an octagenerian Charlie Chaplin stands on a darkened stage while clips of the real Charlie Chaplin’s films play behind him. (In an interesting bit of casting in the same movie, Geraldine Chaplin has a major role as her own nutty grandmother.)
OK, I’m sure this also not what you had in mind, but Audie Murphy famously played himself in To Hell and Back, which in itself would technically qualify as appearing and being portrayed in the same film. But he was also portrayed by another actor (Gordon Gebert) as a child.
Little Richard plays himself in the present day scenes of “Why Do Fools Fall In Love” and then someone else plays him (Miguel A. Nunez, Jr.) in the flashback scenes.
Tina Turner is portrayed by Angela Bassett in “What’s Love Got to Do With It” but then plays herself in the very last scene when she’s performing.
Gene Hackman played Popeye Doyle, a fictionalized version of real-life cop Eddie Egan in The French Connection. Egan appeared in The French Connection as Simonson
Al Jolson appears briefly in Jolson Sings Again, his film biography. Jolson wanted to play the role, but was refused, and the producers didn’t want him for a cameo, though he managed to get one.
Eddie Egan – the basis for Popeye Doyle – made a brief appearance in The French Connection.
Arlo Guthrie and William “Officer Obie” Obanheim played themselves in the movie Alice’s Restaurant.
Though not quite what was asked, Geraldine Chaplin played her own real-life grandmother in Chaplin.
Actually, that was a two-part biopic; The Jolson Story and its sequel, Jolson Sings Again.
Jolson appears as himself in a long shot in Story, but the real mind-blower in Jolson Sings Again is a scene where Larry Parks (who plays Jolson in both films) meets Larry Parks (playing himself, just after being cast to play Jolson in Story). The real Jolson has a momentary cameo in Sings Again as a man watching the filming of Story.
The real Jolson provided the singing for both films, incidentally.
Jann Wenner, publisher of Rolling Stone, had a cameo in Almost Famous and was also portrayed by a young actor in the same film.
Gary D’Addario played a bit part in Homicide: The Movie. A real-life police lieutenant, the character of Lt. Giardello (played by Yaphet Kotto in the series and movie) was based on him.
Harvey Pekar was briefly in American Splendor.
IIRC, Tina Turner appeared briefly at the end of What’s Love Got to Do With It?
Some of the people in the gravesite scene at the end of Schindler’s List were portrayed by younger actors earlier in the film.
Child and teen actors portrayed Howard Stern in the early part of Howard Stern’s Private Parts. His then-wife Alison had a blink-and-you’ll-miss-it part as a telephone operator, and was portrayed by Mary McCormack.
In “Midnight in the Garden of Good and Evil” real lawyer Sonny Seiler played the judge. Got to chew himself out. (There were also a couple of locals playing themselves, notably Lady Cablis. Don’t know about Uga.)