Raised outside of Chicago as the sixth of nine children, including older brother James, a founding member of the band Chicago.
Left college in his junior year after seeing David Mamet's play, The American Buffalo, which inspired Pankow to enroll in the two-year training program at Chicago's St. Nicholas Theater.
Performed on Broadway (in his first stint) in Serious Money, The Iceman Cometh and as Mozart in Amadeus.
Appeared in a numerous films of the late 1980s-early '90s, including To Live and Die in L.A.,Talk Radio and Mortal Thoughts.
Most recognized for his role as Ira Buchman, cousin of Paul Reiser's character, on the '90s NBC sitcom Mad About You.
Returned to Broadway in the 2000s, performing in Twelve Angry Men, The Prime of Miss Jean Brodie and Cymbeline.
Took over the role of Merc Lapidus (from Thomas Haden Church) in 2011 on the Showtime/BBC show Episodes.