Marc Maron - Mark the Shark, Marc Maron
Jim Earl - Mort Mortensen, Cardinal Milfingotn, Mort Milfington, Sammy the Stemcell, Todd Brad, Jim Earl
Kent Jones - Lawton Smalls, Angus McFarquhar
Barry Lank - NSA Guy, Al Qaeda News
Mike Ferrucci - Johnny K Street, Al Qaeda News
Bruce Cherry - Bruce Cherry
Iris Bahr - Svetlana
Wyatt Cenac - Lt. Ronnie Rudolph
Mike Leffingwell - Tom Cruise, Anti fat High School Principal
Seth Morris - Jeff DiCarlo
Kevin Katoaka - Jokes
Spencer Dobson - Jokes
Ray James - Jokes
Steve Rosenfield - Jokes 

There are more but these were the primary TMMS characrters. If you've got specific questions as to who was who for charcacters that weren't regulars or one time bits and I didnt list them post the questions and I'll tell you who it was. I can't recall all.