Keir O'Donnell is an Australian–American actor, best known for his roles in the films Wedding Crashers (2005), The Break-Up (2006), Paul Blart: Mall Cop (2009) and American Sniper (2014), as well as numerous television appearances.

Upon graduation he joined the first class of the newly created four-year classical theatre acting conservatory at The Hartt School in Hartford, Connecticut.

In the fall of 2001 he was cast as a lead in the U.S. premiere of The Man Who Never Yet Saw Woman's Nakedness by Moritz Rinke, at The Odyssey Theatre in West Los Angeles.

[citation needed] After several student and independent films, O'Donnell landed the role of Todd Cleary in Wedding Crashers.

[3] In 2011, he had a recurring role on the Showtime series United States of Tara, appearing for the second half of the third season as Evan, Kate's love interest.