His family left Glasgow when McTavish was a child, and throughout his adult life, he has lived in places such as Canada, the United States, and England before settling in New Zealand.

[4][5] During school, McTavish and a friend would write and perform comedy sketches, which led to his drama teacher asking him to step in to cover a role in Sheridan's The Rivals after the principal actor became ill.

[51] In 2016, McTavish landed the recurring role of William Munny, the Saint of Killers in AMC's drama Preacher, which is based upon Garth Ennis and Steve Dillon's comic book series of the same name.

[52][53][54] 2018 saw McTavish feature in the recurring role of Andrew MacGregor in USA Network's science fiction series Colony, which explores earth after an alien attack.

In 2021 McTavish also joined the cast of Netflix's fantasy drama The Witcher, based upon author Andrzej Sapkowski's book series, as master spy and Redanian Intelligence head Sigismund Dijkstra.

[60][61] For Queen and Country (1988), a social drama from director Martin Stellman, featured McTavish opposite Denzel Washington in his first professional film role.

[62] The next year he had a small part in Terry Jones' mythological comedy Erik the Viking, which was written and performed in the style of a Monty Python film.

[63] Working once again with Jones, McTavish portrayed a drunken weasel in 1996's Mr. Toad's Wild Ride, an adaptation of Kenneth Grahame's children's classic The Wind in the Willows.

[72] In 2008, McTavish starred opposite Sylvester Stallone in Rambo, the fourth film in the franchise based upon David Morrell's 1972 novel First Blood.

[75][76][77][78][79] In 2010, McTavish had a supporting role in Disney's Secretariat, based upon the true story of Penny Chenery and the racehorse who would win the first American Triple Crown in twenty-five years.

[83][84] McTavish completed 2014 with a supporting role in the action adventure film Plastic, opposite Ed Speleers, and director Jonathan King's independent sci-fi thriller REALITi.

[85][86] The next year he portrayed Ricky Conlan (Tony Bellew)'s boxing trainer Tommy Holiday in Creed, the seventh film in the Rocky franchise.

[87] Disney's The Finest Hours, based upon the true story of a daring Coast Guard rescue in 1952, saw McTavish co-star opposite Chris Pine and Eric Bana in 2016.

[89] In 2017, McTavish starred in director Niall Johnson's western thriller The Stolen, followed by a cameo as King Atlan in the DC Comics/Warner Brothers film Aquaman.

[93] Later that same year, it was announced that McTavish would star, opposite Anne Heche, in Specter Pictures' upcoming horror thriller Chasing Nightmares.

[106][107] From there, between 2015 and 2017, he had a recurring voice role in Nickelodeon's animated series Teenage Mutant Ninja Turtles and a guest spot in an episode of Kung Fu Panda: Legends of Awesomeness (2016).

[118][119] He would go on, in 2009, to portray Commander Lucius in Epic Games' Shadow Complex, Crimson in Tecmo Koei's Ninja Gaiden Sigma 2, Arl Eamon Guerrin in BioWare's Dragon Age: Origins, Archer in Activision's Call of Duty: Modern Warfare 2, and Wilcox in Electronic Arts' The Saboteur.

[12][120][121][122][123] McTavish also provided both the voice and motion capture work for the main antagonist Zoran Lazarević in action-adventure game Uncharted 2: Among Thieves.

[125][126][127][128][118][129] In 2011, McTavish provided the voices of antagonist Joseph Bertrand III in Infamous 2, an imperial guardsman in Warhammer 40,000: Dawn of War II – Retribution, a ClawHammer soldier in SOCOM 4: U.S. Navy SEALs, Caddoc in Hunted: The Demon's Forge, and Ivan Stagleishov in Ace Combat: Assault Horizon.

[100][118][142] In 2020, McTavish and fellow Outlander actor Sam Heughan published a book entitled Clanlands: Whisky, Warfare, and a Scottish Adventure Like No Other, which was inspired by their work on the upcoming STARZ docu-series Men in Kilts.