Dunn appeared in many live performances in Chicago and its suburbs, including the theater companies Northlight, Remains, Wisdom Bridge and Goodman before his TV and motion picture career. Dunn's work includes
Samantha Who?, a series appearing on ABC from 2007 to 2009, as well as playing
Ron Witwicky in
Michael Bay's
Transformers film series. His film appearances include
Ghostbusters II (1989),
Hot Shots! (1991),
1492: Conquest of Paradise (1992),
Dave (1993), ''
Beethoven's 2nd (1993), Nixon (1995), Mad Love (1995), Small Soldiers (1998), Godzilla (1998), Snake Eyes (1998), and Stir of Echoes (1999). Dunn also played Murry Wilson in a 2000 miniseries, The Beach Boys: An American Family''. He played President
Richard Nixon's
White House Counsel,
Charles Colson, in
Nixon and played President
Bill Clinton's
National Security Advisor,
Sandy Berger, in the
ABC miniseries
The Path to 9/11. In 2000, he co-starred in
Bette, a sitcom starring
Bette Midler, in which he played her husband in the show's first 11 episodes. From 2004 to 2006, Dunn had a small recurring role as Terry Hardwick, a baseball coach and mentor to
Tyler Hoechlin character
Martin Brewer, on the long-running family drama
7th Heaven. Dunn played Joel Horneck,
Jerry's overzealous childhood friend, in the
Seinfeld episode "
Male Unbonding". He has also featured in
Live Free or Die as well as the 2006 film
Gridiron Gang. Dunn is an executive producer of the award-winning documentary film
Kumpanía: Flamenco Los Angeles (2011). Dunn played the role of White House Chief of Staff
Ben Cafferty in HBO's late 2010s political comedy
Veep. == Personal life ==