 Interested in acting since he was a child, young Brett was employed as a page at CBS Television studios, where he met Jack Benny and Benny's wife, Mary Livingstone, who presented him to William Goetz, the head of Universal Pictures, who placed him in a school with other aspiring actors for the studio.Halsey appeared as Swift Otter, a Cheyenne Indian in the 1956 episodes "The Spirit of Hidden Valley" and "The Gentle Warrior" of the CBS western series, "Brave Eagle", starring Keith Larsen as a young Indian chief.In 1958, Halsey guest-starred several times as Lieutenant Summers in Richard Carlson's syndicated western series, "Mackenzie's Raiders", a fictional account of cavalry Colonel Ranald S. Mackenzie, set at Fort Clark, Texas.