John was born in St. Louis and grew up in Chicago, where he was one of nine children. During his high school years, he dabbled in drama, but it wasn't until he enrolled at Northeastern Illinois University to study theater arts that he became serious about acting.
However, his time at the university was cut short when he attended a performance of David Mamet's "The American Buffalo" at the St. Nicholas Theater in Chicago. Inspired by the play, he left the university in his junior year to enroll in the theater's two-year theatrical training program, allowing him to focus solely on acting.
After completing his training, Pankow visited a friend in New York City and auditioned for, and won, a role in a PBS film titled "Life on the Mississippi" in 1980. He went on to perform in several off-Broadway productions, including "Scheherazade," "Aristocrats," "Italian American Reconciliation," "Hunting Scenes," "Ice Cream/Hot Fudge," and the New York Shakespeare Festival's "Two Gentlemen of Verona" and "Henry VIII."
Pankow's breakthrough to Broadway came with roles in "Serious Money," "The Iceman Cometh," and as Mozart in "Amadeus," one of his most notable roles to date. He has since reprised his role as Stefano in the hit production of Shakespeare's "The Tempest" in Central Park.
In addition to his theater work, Pankow has appeared in several motion pictures, including "A Stranger Among Us" (1992),"Mortal Thoughts" (1991),"Talk Radio" (1988),"To Live and Die in L.A." (1985),and "The Secret of My Success" (1987).
On the television side, Pankow has made guest appearances on shows such as "Law & Order" (1990),"Spenser: For Hire" (1985),and "Miami Vice" (1984). He was later signed as a cast regular for the first season of "Mad About You" (1992).
Currently, Pankow is involved in developing projects for himself in the theater, both as an actor and director. In his free time, he enjoys cooking for his wife and their daughter.