michael james mcdonald (born december 31, 1964) is an american stand-up comedian, actor, director, and writer. he is best known for starring in the sketch comedy show "madtv" and for voicing numerous characters on "the simpsons" from 1998 to 2010. mcdonald joined the show during the fourth season (1998) and remained in the cast until the end of the thirteenth and penultimate season, having become the longest-tenured cast member.