Timothy John Costelloe, SDB (born 3 February 1954) is an Australian Catholic prelate who has served as Archbishop of Perth since 2012.

Professed as a Salesian in 1985, Costelloe was ordained as a priest on 25 October 1986 by Archbishop Sir Frank Little in Melbourne.

Transferred to Perth in 1996, Costelloe served as parish priest St Joachim's Victoria Park and lectured at the University of Notre Dame Australia, Fremantle.

He returned to Melbourne in 1999, was appointed as rector to the Salesian community, and resumed teaching commitments at the Catholic Theological College.

[1] In February 2012 Pope Benedict XVI named Costelloe to succeed Barry Hickey as Archbishop of Perth.