Garret grew up in the state of Washington and attended the University of Washington where he studied journalism. He received his MFA from New York University's Graduate Acting Program. He appeared on and off Broadway and in theaters around the country before he began pursuing film and television roles. He has two brothers: Brett, a teacher; and Eric, deceased.
Prior to his casting, he auditioned for The Walking Dead for the role of Negan but did not get the part.
- The Gifted
- The Mindy Project
- Hand of God
- 12 years a Slave
- The Last House on the Left (2009 Remake)
- No Country for Old Men
- Raising Hope
- Terminator: The Sarah Connor Chronicles
- John from Cincinnati
- One Life to Live
- Burn Notice
- He previously appeared on Deadwood along with fellow Fear the Walking Dead actors Kim Dickens, Dayton Callie, and Ray McKinnon.
- As of 2016, has appeared in three films that were nominated for the Best Picture Oscar: No Country for Old Men (2007), Winter's Bone (2010) and 12 Years a Slave (2013). Of those, No Country for Old Men (2007) and 12 Years a Slave (2013) are winners in the category.