He is best known for his role as Adam Moseby in Bugs, Andy Button in the television series Episodes, Paul who was the boyfriend of Sam Colloby, in Casualty, Luke in I Live with Models and for voicing Thomas the Tank Engine in the US dub of the children's television series Thomas & Friends from 2015 to 2021.

Joe: Valor vs. Venom, Mr. Wexler in The Barbie Diaries, Autolycus in Class of the Titans, Michael Corleone in The Godfather, Perdido in Xenoblade Chronicles 2, Chase McCain in Lego City Undercover, Jost and Saravad in Horizon Zero Dawn, Hiro in The Crew 2 and Ellis in Blair Witch.

Born in England and raised in Calgary, Alberta, Canada, May returned to the United Kingdom to study at the London Academy of Music and Dramatic Art.

May may be most recognised by British-American television viewers as Paul, the unemployed partner of gay nurse Sam Colloby in Casualty's 12th season.

Since then, he has appeared in the critically acclaimed World War II miniseries Band of Brothers as second lieutenant Edward Shames, 2001's Investigating Sex as Roger, Resident Evil as Dr. Blue and Holby City as surgeon George Kerwan in 2010.