Theophilus was the son of William Bird, an actor long associated with the theatrical enterprise of Philip Henslowe and active in the years 1597–1622.
The younger Bird started out as a boy player acting female roles, as was customary at the time; he played Paulina in Massinger's The Renegado for Queen Henrietta's Men in 1625.
[1] Like most boy actors, Bird moved on the adult roles, like Masinissa in the company's 1635 production of Thomas Nabbes's Hannibal and Scipio.
He was one of the fifteen men — Thomas Killigrew, Sir Robert Howard, and thirteen actors — who signed the 28 January 1661 agreement that defined the sharers in the King's Company.
He resumed stage work after his recovery, and played Prospero in Richard Rhodes's comedy Flora's Vagaries on 3 November 1663.