McKenna is 6' 2" tall and trained at the Mason Gross School of the Arts at Rutgers University. He has appeared in a number of films, TV series and on stage. In 2002 he was nominated for the Outer Critics Circle Award for Outstanding Featured Actor for his role in The Golem directed by Lawrence Sacharow.
McKenna's filmography includes:
- Person of Interest (TV series) (2015)
- Shutter Island (2010)
- Life on Mars (TV series) (2007)
- Law and Order: Special Victims Unit (TV series) (2003)
- The Long Kiss Goodnight (1996)
- 12 Monkeys (1995)