Greg Tiernan (born on 19 June 1965 in Dublin, Ireland) is an Irish-born Canadian animator, director, producer and voice actor. He is the Chief Creative Officer and co-founder of Nitrogen Studios. He was the director of Thomas & Friends from 2008 to 2012. He began work directing the series after the CGI transition, taking over from Stephen Asquith.

He was replaced by David Baas when production was moved to Arc Productions in 2012.

He was born in Ireland and started Nitrogen Studios in 2003 with Nicole Stinn.

Other work includes, "The Land Before Time", "An American Tail", "All Dogs Go To Heaven", "Happily N'Ever After", "Trollhunters" and "Sausage Party".






  • "Sausage Party" (2016)


  • "City in Crisis" (2015)


  • He is married to Nicole Stinn.
  • He has been working in the animation industry for twenty-seven years.
  • Tiernan is a fan of the Railway Series. So much in fact, that he owns a copy of both The Island of Sodor: Its People, History and Railways and Sodor: Reading Between the Lines.
  • According to an interview with SiF, Greg Tiernan says he would like to remake Pop Goes the Diesel and Dirty Work. And, if it was his choice, he would reintroduce every character ever introduced.
  • Tiernan was involved in the animation of "Happily N'Ever After", the last film in which George Carlin played a part.
  • In an interview on 98.3 Vancouver, Tiernan told the hosts of the radio station the reason why they stopped working on Thomas, was due to the fact that they only wanted their team to focus on one project instead of doing multiple projects at the same time. But did enjoy working on the show while it lasted.