Mann was born in Middlebury, Vermont, to Alice Jo (née Amis), an attorney, and Stephen Smith Mick, a sociology professor.

[6] Mann played one of the lead roles in the psychological thriller Psych 9 with Sara Foster, Cary Elwes, and Michael Biehn.

[7][8] Mann appeared in episodes of the television series ER, Fantasy Island, Jeremiah, Carnivàle, Wasteland, Time of Your Life, and Legend of the Seeker.

[9] He also voiced Bruce Banner in the animated series The Avengers: Earth's Mightiest Heroes and Wolverine and the X-Men, which are set in the same continuity.

In May 2012, Mann joined the ensemble cast of Diego Luna's biopic film Cesar Chavez, alongside Michael Peña, America Ferrera, Rosario Dawson, John Malkovich, and Wes Bentley.