O'Gorman was born in Auckland, New Zealand, the son of Vicky and Lance O'Gorman, a landscape painter. He has a brother named Brett. He attended Rangitoto College and earned a black belt in karate by the age of ten.
Got his start in the television movie, The Rogue Stallion at the age of fourteen, and Raider of the South Seas, both of which were released in 1990. He then won the role of Nurse Harry Martin in the New Zealand soap opera, Shortland Street and has appeared in both Hercules and Xena multiple times, as well as a recurring role as young Iolaus in Young Hercules, co-starring Ryan Gosling. More recently, he has made multiple guest appearances on shows such as, The Cult, Go Girls and Legend of the Seeker and currently plays the role of Anders Johnson on The Almighty Johnsons. In April 2011, he was cast as Fíli in Peter Jackson's The Hobbit films.
Richard Armitage • John Bell • Manu Bennett • Cate Blanchett • Orlando Bloom • Jed Brophy • Adam Brown • John Callen • Benedict Cumberbatch • Luke Evans • Martin Freeman • Stephen Fry • Ryan Gage • Mark Hadlow • Peter Hambleton • Craig Hall • Sir Ian Holm • Stephen Hunter • Robin Kerr • William Kircher • Sir Christopher Lee • Evangeline Lilly • Sir Ian McKellen • Graham McTavish • James Nesbitt • Mary Nesbitt • Peggy Nesbitt • Dean O'Gorman • Lee Pace • Mikael Persbrandt • John Rhys-Davies • Andy Serkis • Conan Stevens • Ken Stott • Aidan Turner • Hugo Weaving • Elijah Wood