Mackenzie Gray was born and raised in Toronto. A professional actor for over 40 years, he has appeared in over 150 films and television shows. As of 2017, he is a series regular on the Marvel/FX Series Legion (2017) playing "The Eye" and is a recurring cast member on both the CW series Riverdale (2016) as "The Pathologist" and plays "The Time Master" on DC's Legends of Tomorrow (2016).

Since moving to Vancouver in 1998 as a series lead for the television series The Net(1998), he has appeared as a guest star in scores of Vancouver or Calgary-filmed productions, recently including the BBC America/Netflix series Dirk Gently's Holistic Detective Agency (2016), Fargo (2014), R.L. Stine's The Haunting Hour (2010), Alcatraz(2012), and Project Mc² (2015). He returned to Toronto to Guest-Star in the series Bitten(2014).

Guest-Starring roles include "John Amos" in If There Be Thorns (2015), "David Bowie" in Some Assembly Required (2014), "Lex Luthor" in Season 10 of Smallville (2001), "The Djiin" in Supernatural (2005), "The Observer" in the series finale of Fringe (2008), as the Devil, in the form of Keith Richards, in R.L. Stine's The Haunting Hour (2010), as a Southern U.S. Senator opposed to Civil Rights in the mini-series The Kennedys (2011) and as a Graphic Novelist with a dark secret again in R.L. Stine's The Haunting Hour(2010).

Other Guest-Star or Lead roles include work on the TV series Human Target (2010), Young Blades (2005), Da Vinci's Inquest (1998), The Collector (2004), First Wave (1998), So Weird (1999), Once Upon a Time (2011), True Justice (2010), The Bridge (2010), Sanctuary (2008), Psych (2006), Kyle XY (2006), The L Word (2004), Romeo! (2003), The Twilight Zone (2002), Babylon 5: The Legend of the Rangers: To Live and Die in Starlight (2002), Big Sound (2000), Andromeda (2000), Cold Squad (1998), Voyage of the Unicorn (2001) and Welcome to Paradox (1998).

Mackenzie was recently seen on the big screen in Warcraft: The Beginning (2016), and was celebrated around the world for his portrayal of "Jax-Ur" in Warner Brothers' Zack Snyder-directed Superman film Man of Steel (2013). He appeared as the band's Road Manager in Metallica's 3-D IMAX Feature Metallica Through the Never (2013) and appeared in Terry Gilliam's The Imaginarium of Doctor Parnassus (2009). Other feature film work includes co-starring roles in Grave Encounters (2011), Shooter (2007), Storm Seekers (2009), Riddles of the Sphinx (2008), Destination: Infestation (2007), Joy Ride 2: Dead Ahead (2008), Strip Search (1997), Christmas on Chestnut Street (2006), 2103: The Deadly Wake (1997), Word of Honor (2003), The Hitcher II: I've Been Waiting(2003), Falling Fire (1997), In Her Mother's Footsteps (2006), Hard Ride to Hell (2010), Shepherd (1998), Fugitives Run (2005), Replikator (1994) and The Long Kiss Goodnight(1996).

He co-produced and acted in the upcoming feature film Heart of Clay (2017), and the award-winning feature film Poe: Last Days of the Raven (2008). Mackenzie has written, produced and directed 7 short films. His Crazy 8's Film Noir short Under the Bridge of Fear(2013) screened at Cannes Court Métrage at The Cannes Film Festival, the Vancouver International Film Festival, the Whistler Film Festival and was broadcast by the CBC. It was nominated for 10 LEO Awards, winning one.