He is known for his roles as Clay Jensen in 13 Reasons Why , David Shephard in Lost , Rex Britten in Awake , Anthony in Alexander and the Terrible , Horrible , No Good , Very Bad Day , Zach Cooper in Goosebumps , Jerry Fitzgerald Jr. in Scandal , and Alex in Do n't Breathe.
The character Clay Jensen in 13 Reasons Why has the nickname `` Helmet '' .