1. Peter Sellers (1925-1980) Tops the list because he's the only actor ever to be nominated for the Academy Award for playing 3 different parts * - Captain Lionel Mandrake, President Merkin Muffley, and the title character in DR. STRANGELOVE. He was even originally going to play a 4th character - Major T.J. 'King' Kong but he was uncertain of his ability to do a Texan accent so the role went to Slim Pickens. Sellers came from a sketch comedy radio background as a member of the Goons (with Spike Milligan, Michael Bentine, and Harry Secombe) so he was well equipped early on to handle tons of assorted dialects. 9 out of the roughly 35-40 movies he made (depends on which filmography you read) had him playing over 25 different parts. 
The range of accents, change of genders and ethnic makeovers throughout his career makes it difficult to know how his real voice (if there actually was one) sounded and what he really looked like in real life - though to him there probably was no such thing as "real life".The most notable of the films in which the master inhabits more than one personage is THE MOUSE THAT ROARED (3 characters), LOLITA (2 characters), the original 1967 CASINO ROYALE (just 2 characters but one was James Bond!) and the little seen SOFT BEDS, HARD BATTLES in which 2 of the 6 parts he played were Hitler and the President. His final film - the dismal THE FIENDISH PLOT OF DR. FU MANCHU had him play 2 characters - the villain of the title and who he considers his "worthy adversary" - Dr. Hayland Smith. Not the greatest exit in cinema history but at least he went out doing what he did best.
2. Eddie Murphy - I'm sure many readers will be cynical about Murphy being this high on the list but just consider this : he's played more characters in a fewer amount of movies than Sellers and he has convincingly portrayed 
an entire family (aided by CGI) through 2 incredibly profitable if not acclaimed films (THE NUTTY PROFESSOR & NUTTY PROFESSOR II : THE KLUMPS). It worked so well in a movie as cheesily charming as COMING TO AMERICA that I can overlook the device in such crap as VAMPIRE IN BROOKLYN and NORBIT. So even if Murphy spends the rest of his days doing the Donkey in future SHREK sequels or resurrecting Axel Foley every now and then for a fast buck he's still got his multi-tasking part playing skills to fall back on.
3. Monty Python (1969-1983) - Okay so many readers wrote me to say that they felt the Python players (Graham Chapman, John Cleese, Terry Gilliam, Eric Idle, Terry Jones, and Michael Palin) got short shrift in my 10 Definitive Films-Within-Films and 10 Movie Moments That Broke The 4th Wall posts so I’m giving them full due here. Part of the powerful charm of the original BBC Flying Circus program, which was heavily inspired by the Goons (Sellers again!), was that each of the 5 performing members played a bunch of parts in various sketches every episode. Even animator Terry Gilliam, so not an actor, put in a few memorable moments. When it came to their movie work no other films in comedy movie history were as peopled by, well, the same people over and over. I’m not going to list everybody’s exact standing in multiple role-dom but just for example’s sake here’s the most popular Monty Python member John Cleese’s stats :
AND NOW FOR SOMETHING COMPLETELY DIFFERENT (1971) - 15 characters.MONTY PYTHON AND THE HOLY GRAIL (1975) - 7 characters.
MONTY PYTHON’S THE LIFE OF BRIAN (1979) - 6 characters.
MONTY PYTHON LIVE AT THE HOLLYWOOD BOWL (1982) – 12 characters.
MONTY PYTHON’S THE MEANING OF LIFE (1983) - 9 characters.
Whew! That’s 49 different characters in just 5 movies – quite a run, huh? Figure in all the other Python players and their plethora of parts and you’ve got the biggest tally of multiple characters in cinema history. Can’t tell you the exact tally though – too lazy to do the math.
Postnote #1 - Maybe it seems lame to have the Python troupe under one entry but a list where each member was given their own slot would have been tedious - therefore lamer - so I opted for a one for all entry.
Postnote #2 - Carol Cleveland : From Flying Circus to Meaning Of Life she was the unsung female reparatory member. For a list like this that should be noted.
4. Lily Tomlin - Sure, she hasn't been in as many movies where she plays multiple roles as some of the others on this list but for 3 solid reasons she makes the top 5 - 1.) The only highlights of the dire mostly unfunny sci-fi spoof THE INCREDIBLE SHRINKING WOMAN (Dir. Joel Schumacher - go figure! 1981) was in addition to her playing the title character and neighbor the pursed lipped Judith Beasley there was the bringing to the big screen the classic Tomlin character Ernestine - the persnickety telephone operator from Laugh-In. 2.) This list is way too male dominated and we need Tomlin to break up this sausage party. 3.) It's her BIRTHDAY Damnit! She was born in Detroit on September 1st, 1939 - to be exact. So let's give her props, okay? Though I didn't want to include when someone played their own sibling on this list - she did that duty in BIG BUSINESS (Dir. Jim Abrahams, 1988) with Bette Midler playing her own twin sister as well. Also since I made the exception with the Pythons on sketch films and live performance movies - Tomlin's THE SEARCH FOR SIGNS OF INTELLIGENT LIFE IN THE UNIVERSE (Dir. John Bailey, 1991) has her performing 5 different character pieces. So I believe she fully qualifies. Happy Birthday Lily!
5. Mike Myers - The shadow of Peter Sellers hangs over just about everybody on this list. But it practically burns through the work of Mike Myers. Especially in the AUSTIN POWERS trilogy (AUSTIN POWERS - INTERNATIONAL MAN OF MYSTERY ('97), THE SPY WHO SHAGGED ME ('99), and GOLDMEMBER ('02) which all echo with swinging Sellers as much as they do the swinging '60's London scene. The obvious concept of playing the hero and the villain (Dr. Evil) as well as the bumbling demeanor also present in supporting characters Goldmember and Fat Bastard (also played by Myers) is pure Sellers derived through and through. From the springboard of early 90's SNL Myers has been blending Sellers methods with his own 2nd generation slacker stoner charm in his movie material and has pulled off some tricky double and triple duty so he slides right in at #5.Honorable Mention :
Mel Brooks - Throughout the movies he directed and starred in that were mostly genre spoofs (BLAZING SADDLES, HIGH ANXIETY, HISTORY OF THE WORLD PART I, SPACEBALLS, ETC.) Brooks usually played 2-3 characters each time out. They weren't truly different from one another and that was precisely the joke - maybe not the greatest joke but hey - what can you do?
Meg Ryan - Okay so this violates the rule * that it can't just be somebody playing their sibling (which I know already got broken with Lily Tomlin above) but in addition to sisters Angelica and Patricia Graynamore, Ryan also plays Tom Hanks' office co-worker Dede in the 1990 surreal comedy JOE VS. THE VOLCANO. In his entry on this film Case File #40 of My Year Of Flops Nathan Rabin of the Onion AV Club writes "now normally the phrase 'Meg Ryan in multiple roles' is enough to send shivers down the spine or suggest a fate worse than death. And while it pains me deeply to write this, Meg Ryan is adorable!" I concur so let nobody ever say film babble never gave a shout out to Meg Ryan! Now let's move on.* Also the rule that the actor needs to have been in more that one film playing multiple parts but ah...sue me!
The Kids In The Hall : BRAIN CANDY (Dir. Kelly Makin, 1996) Not quite up to Python standards, oh Hell not even up to SCTV standards the Canadian comedy quintet (Dave Foley, Kevin McDonald, Bruce McCulloch, Mark McKinney, and Scott Thompson) had a good run on TV so why not a full fledged feature with each member playing multiple parts? Sounds great! Wait - key member Dave Foley doesn't really want to take part? Oh okay, he'll do a few bits but won't contribute to the writing? Hmmmm, maybe the whole project should be scrapped - what everybody wants to do it anyway? Okay, It might work. What? It didn't? Damn. Kind of like the last season of Flying Circus in which John Cleese didn't participate, BRAIN CANDY has some good bits but nothing classic. The Pythons though regrouped with HOLY GRAIL - doubt the Kids will ever pull off something like that.Also according to Wikipedia : "Lon Chaney played dual roles in several films, using the elaborate makeup that became his trademark." I'll take your word for it Wikipedia!
Okay, so that's all I got for now. So before you say Martin Short - I know there are lots and lots of multiple part players I missed so shoot 'em on over!
More later...
