John Hansen is best known for The Returning, The Executioner's Song, The Time Machine, and The Christine Jorgensen Story. Other film credits include Uncommon Valor, California Gold Rush, The Adventures of Nellie Bly, Earthbound, Beyond Death's Door, Donner Pass: The Road to Survival, and Incredible Rocky Mountain Race.

Theatre credits include his Broadway debut as Hero in A Funny Thing Happened on the Way to the Forum (Lunt-Fontanne Theatre) and regionally, as the Orderly in The Talking Cure (Mark Taper Forum), Bill in Ventriloquist Sex (Urban Ensemble), Cyrano in Cyrano (San Jose Repertory), Valentine in You Never Can Tell (Yale Repertory), Trofimov in The Cherry Orchard (Santa Fe Stages), Albert Mondego in The Count of Monte Cristo (Pioneer Theatre), Frank Harris in Gross Indecency (Caldwell Stage), Valentine Coverly in Arcadia (TheatreVirginia), Orlando in As You Like It (Folger Theatre), Alexander Berkman in Emma (Motherlode Theatre), and Iago in Othello (Maryland Stage).