The actor will play Agent Grant, described as one of S.H.I.E.L.D.'s "highly-skilled rising stars" and "deadly, precise, and cool under fire -- but not so great with the people skills."
Brett Dalton is known for Army Wives and Blue Bloods as well as the upcoming Killing Lincoln TV movie.
He joins Clark Gregg as Agent Phil Coulson, Ming-Na Wen as Agent Melinda May, Elizabeth Henstridge as Agent Gemma Simmons and Iain De Caestecker as Agent Leo Fitz.
The S.H.I.E.L.D. series is said to begin filming this January for a possible Fall premiere.
Cosmic Book News is still hopeful for a Wendell Vaughn, Quasar, appearance.