Famous for his series regular role as Neil Sutherland on the television series The Inbetweeners, he is also notable for his recurring roles on Big Love, Betas, and Dexter. In 2014, playing the role of Tyler Beck, he joined the cast of The Comeback.
When he was just twelve years old, he appeared in episodes of Still Standing and Six Feet Under.
His film credits include roles in We're the Millers (as Scottie P), The Lucky Ones (as Scott Cheaver), and Tammy (as Jesse).
A native of Everett, Washington, Mark L. Young (born Markell V. Efimoff) relocated to Hollywood in his late childhood years.
He and Josh Zuckerman were both in the cast of the 2008 comedy movie Sex Drive.