Kay was born at St Pancras, London and is the son of actor Richard Kay (1937–1987) and Jaqueline (née Maxwell) and the grandson of entertainer Arthur Kay (died 1970).
He met actress Nicola Walker when they worked together with the Out of Joint Theatre Company, in a 1994 touring production of The Man of Mode and The Libertine;1 they married in 2006, and have a son together.2
Among other roles, Kay has appeared in The Five (2016), Wallander (2012–15), Doctor Who (2015), New Tricks (2013–14), Frankie (2013), Public Enemies (2011), Wuthering Heights (2009), Holby City (2008), Midsomer Murders (2005), Spooks (2004), Prime Suspect (2003), Serious and Organised (2003), Silent Witness (2002), Conspiracy (2001), The Bill (2000), Casualty (1999), Shakespeare in Love (1998), Croupier (1998), Jonathan Creek (1997), Cracker (1996), The Vet (1995) and Minder (1994).
Kay's theatre work includes A Streetcar Named Desire at the Donmar Warehouse (2009),3 Orlando in As You Like It at the Novello Theatre (2006), Closer at the National Theatre (1999–2000), Pierre Bezuhov in Warring Peas at the Hampstead Theatre (2008), Tinky Winky, Teletubbies tour (2011-2016), Steve Calhanm in Eric Larue at the Soho Theatre (2006), and Alexander Petrovich Kalabushkin in Dying For It at the Almeida Theatre (2007).4
"Past Productions: The Man of Mode / The Libertine | by George Etherege, Stephen Jeffreys | 1994". Out of Joint Theatre Company. 1994. Archived from the original on 19 May 2021. Retrieved 2 January 2025. ... at the University of Warwick Arts Centre on 20 October 1994 and then on tour, culminating at the Royal Court Theatre, London, on 6 December 1994. https://www.outofjoint.co.uk/production/the-man-of-mode-the-libertine/ ↩
Palmer, Katie (9 May 2022). "How did Nicola Walker meet husband Barnaby Kay?". Daily Express. Archived from the original on 18 February 2024. Retrieved 18 February 2024. The pair were together for almost 20 years before they married in 2006. https://www.express.co.uk/showbiz/tv-radio/1607694/Nicola-Walker-meet-husband-Barnaby-Kay ↩
whatsonstage.com Archived 16 June 2011 at the Wayback Machine What's On Stage website http://www.whatsonstage.com/index.php?pg=206&action=details&show=T02102699482 ↩
"Barnaby Kay". London Theatre Database. Archived from the original on 24 July 2011. Retrieved 11 September 2018. https://web.archive.org/web/20110724021709/http://www.ltdb.co.uk/node/8005 ↩
"The Lovecraft Investigations". BBC Radio 4. Retrieved 23 January 2022. https://www.bbc.co.uk/programmes/p06spb8w ↩
"BBC Radio 4 - The Whisperer in Darkness, Ep 1. The Case of Charles Dexter Ward". BBC. 2 January 2019. Retrieved 27 December 2019. https://www.bbc.co.uk/programmes/p06w5zwg ↩
"BBC Radio 4 - The Whisperer in Darkness, Ep 1. The Whisperer in Darkness". BBC. 30 November 2019. Retrieved 27 December 2019. https://www.bbc.co.uk/programmes/p07wnshp ↩
"BBC Radio 4 - the Lovecraft Investigations, Ep. 8 – the Shadow over Innsmouth". www.bbc.co.uk. 19 November 2020. Retrieved 3 December 2020. https://www.bbc.co.uk/programmes/p08yx1ss ↩