In 2000, Mays' debut role was a slot in
EastEnders. Mays started his big screen career in 2001, as a pilot in the film
Pearl Harbor. then in 2008, played the role of Michael Myshkin in
Channel 4's adaptation of
David Peace's
Red Riding trilogy. His appearance in the 2008 independent British crime film
Shifty, co-starring
Riz Ahmed, earned him a nomination for best supporting actor at the
British Independent Film Awards. In 2010, Mays starred as Eddie O'Grady in the film
Made in Dagenham. In the same year, he played
DCI Jim Keats in the third series of
Ashes to Ashes, in which he portrayed a character that was the antagonist of
Philip Glenister's
Gene Hunt. In 2011, Mays appeared in the BBC sci-fi series
Outcasts. He had roles in
No One Gets Off in This Town and a supporting role in the
Steven Spielberg film
The Adventures of Tintin: The Secret of the Unicorn. He then played a criminal on a curfew after serving a 10-year sentence for the murder of his girlfriend when he was 19 in the programme
Public Enemies, which aired on
BBC One in early January 2012. He played
Ronnie Biggs in a 5-part drama called
Mrs Biggs. In 2012, he starred alongside
Gemma Arterton and
Saoirse Ronan in the vampire film
Byzantium. For much of the latter half of 2013, Mays performed on stage. Performing in Nick Payne's
Same Deep Water As Me at the Donmar Warehouse alongside Nigel Lindsay and in the first major revival of Jez Butterworth's debut play
Mojo at the Harold Pinter Theatre. He starred alongside
Ben Whishaw,
Brendan Coyle,
Rupert Grint and
Colin Morgan. In 2016, Mays starred in series 3 of BBC drama
Line of Duty as Sergeant Danny Waldron, an armed response officer whose troubled and abusive childhood comes under investigation as part of wider investigation of police corruption throughout the serial. He was nominated for a BAFTA Television Award for Supporting Actor for his role. In 2016, Mays played the part of Aston in
Harold Pinter's play
The Caretaker directed by
Matthew Warchus at
The Old Vic Theatre in London opposite
Timothy Spall and
George MacKay. The same year, Mays portrayed Tivik in the film
Rogue One: A Star Wars Story. In 2020, Mays starred as lead investigator Detective Chief Inspector Peter Jay in the
ITV three-part television drama miniseries
Des, about the 1983 arrest of the
serial killer Dennis Nilsen, and as Marcus in the
Ibiza based whodunnit series
White Lines. In March 2023, Mays made his musical debut as Nathan Detroit in
Guys and Dolls directed by
Nicholas Hytner at the
Bridge Theatre. He left the production temporarily in July (where the role was taken over by
Owain Arthur) due to filming commitments before returning to it in October. For his performance, Mays was nominated for the
Laurence Olivier Award for Best Actor in a Musical in
2024. ==Personal life==