[1] He is best known for his portrayals of janitor Carl Reed in The Breakfast Club[2] and Detective Donald Schanke in Forever Knight.

Other film appearances include Schepisi's Roxanne,[10][11] with Steve Martin and Daryl Hannah, and Garry Marshall's Nothing in Common,[10] opposite Tom Hanks, and Touchstone’s Stick It.

Those appearances include Miami Vice as a corrupt public defender, Desperate Housewives, Queer as Folk, The X-Files, Seinfeld, Home Improvement, Dead Like Me, ER, and Boston Legal.

[10] He also played a security guard in a 2010 episode of the television series Nikita, filmed at the University of Toronto.

Kapelos also guest teaches at the AIA Studios focusing on improv/acting workshops;[13] produced a four-part series on YouTube featuring monologues by NPR-contributor Michael Raysses called Greek to Me,[14] and manages an independent record label called Carpuzi Records, which has produced sound recordings featuring him and some of the Second City alumni, such as Dan Castellaneta.