Milligan was born in Yellowknife, Northwest Territories, the son of Jean Wallace, a former Yellowknife city councillor, and Brian Milligan.
He is known for playing the role of Ethan Ward in the The CW's 90210, a spin-off of the 1990s primetime drama Beverly Hills, 90210. He was written out of the show at the end of the first season.
His film credits include Final Destination 3 (2006), Slither (2006), The Butterfly Effect 2 (2006), In the Land of Women (with Kristen Stewart, Adam Brody and Meg Ryan) (2007), Butterfly on a Wheel (2007), The Messengers (2007) and Extract (2009).
Milligan starred in the short-lived prime time suspense drama Runaway, picked up by The CW for its inaugural season in September 2006, but cancelled in October after only three of nine episodes completed had been aired.
He starred in the Canadian network CTV's made-for-TV movie Eight Day to Live playing O.C. star Kelly Rowan's missing son. Milligan has also played minor roles in the television series The Days, Andromeda, The Dead Zone, I Think, Supernatural and the CBC's Da Vinci's City Hall.
As part of promoting In the Land of Women, Milligan posted a series of eight video diaries on YouTube with the ostensible aim of obtaining a date for the film's premiere.
Milligan dated his 90210 co-star Jessica Stroup for almost two years before breaking up in August 2010. Since filming Final Destination 3, Milligan has been close friends with actress Amanda Crew, and has worked with her throughout the years in several other projects.
|Amber Frey: Witness for the Prosecution||Grocery Clerk|
|The Long Weekend||Ed|
|A Perfect Note||Ripper|
|2006||Man About Town||Young Dooley|
|Final Destination 3||Marcus|
|Eight Days to Live||Joe Spring|
|Nostalgia Boy||Nostalgia Boy|
|The Butterfly Effect 2||Trevor Eastman|
|In the Land of Women||Eric Watts|
|Butterfly on a Wheel||Matt Ryan|
|2010||Tossers||Jimmy "The Lace" Santino|
|Gunless||Corporal Jonathan Kent|
|2011||Shark Night||Nick LaDuca|
|Sisters & Brothers||Rory|
|The Entitled||Nick Nader|
|2012||The Campaign||College Frat Guy|
|Love at the Christmas Table||Sam Reed|
|2013||The Legend of Sarila||Markussi|
|2004||The Days||Steve Colter|
|Dead Like Me||Joey|
|2005||Da Vinci's City Hall||Chad Markowitz|
|2006||The Dead Zone||Randy|
|Alice, I Think||Mark Conners|
|Runaway||Henry Rader/Jason Holland|
|2008||About a Girl||Stan|
|Supernatural||Alan J. Corbett|
|2012||Call Me Fitz||Barry O'Neil|
|2013||Made in the USA||Demi Lovato||The Boy|