Murphy began his collaboration with filmmaker Christopher Nolan in 2005, playing the Scarecrow in The Dark Knight trilogy (2005–2012) as well as appearing in Inception (2010) and Dunkirk (2017).

He gained greater prominence for his role as Tommy Shelby in the BBC period drama series Peaky Blinders (2013–2022) and for starring in the horror sequel A Quiet Place Part II (2020).

[6] Murphy got his first taste of performing in secondary school when he participated in a drama module presented by Corcadorca Theatre Company director Pat Kiernan.

[9] His first major role was in the UCC Drama Society's amateur production of Observe the Sons of Ulster Marching Towards the Somme, which starred Irish-American comedian Des Bishop.

[8] Murphy pressured Pat Kiernan until he got an audition at Corcadorca Theatre Company, and in September 1996, he made his professional acting debut on the stage, playing the part of a volatile Cork teenager in Enda Walsh's Disco Pigs.

[14] Originally intended to run for three weeks in Cork,[9] Disco Pigs ended up touring throughout Europe, Canada and Australia for two years, and Murphy left both university[5] and his band.

[10] Though he had intended to go back to playing music, he secured representation after his first agent caught a performance of Disco Pigs, and his acting career began to take off.

Released in the UK in late 2002, by the following July, 28 Days Later had become a sleeper hit in North America, and success worldwide, putting Murphy in front of a mass audience for the first time.

His delicate good looks have, as much as his acting prowess, caused people to mark him as Ireland's next Colin Farrell, albeit one who seems less likely to be caught tomcatting around or brawling drunkenly at premieres.

The New York Times film critic Manohla Dargis asserted that Murphy made "a picture-perfect villain" and that his "baby blues look cold enough to freeze water and his wolfish leer suggests its own terrors".

"[43] Murphy starred as Patrick/"Kitten" Braden, a transgender Irish woman in search of her mother, in Neil Jordan's comedy-drama Breakfast on Pluto (2005), based on the novel of the same title by Patrick McCabe.

Seen against the film's kaleidoscopic backdrop of 1970s glitter rock fashion, magic shows, red-light districts and IRA violence, Murphy transforms from androgynous teen to a blonde drag queen.

[10] The role required "serious primping" with eyebrow plucking and chest and leg hair removal,[44] and Roger Ebert noted the way that Murphy played the character with a "bemused and hopeful voice".

[45][46] While lukewarm reviews of Breakfast on Pluto tended to praise Murphy's performance highly,[47] a few critics dissented: The Village Voice, which panned the film, found him "unconvincing" and overly cute.

Murphy considered it a very special privilege to have been given the role and stated that he was "tremendously proud" of the film, remarking that the "memories run very, very deep – the politics, the divisions and everybody has stories of family members who were caught up in the struggle.

[53] Kenneth Turan of the Los Angeles Times wrote that "Murphy is especially good at playing the zealotry as well as the soul-searching and the regret, at showing us a man who is eaten up alive because he's forced to act in ways that are contrary to his background and his training".

Theatre Record described his character of Beane as a "winsomely cranky" mentally unstable "sentimentalised lonely hero", noting how he magnetically, with "all blue eyes and twitching hands", moves "comically from painfully shy "wallpaper" to garrulous, amorous male.

[56] Variety magazine considered his performance to be "as magnetic onstage as onscreen", remarking that his "unhurried puzzlement pulls the slight preciousness in the character's idiot-savant naivete back from the brink".

[60][61] Murphy made a brief re-appearance as the Scarecrow in Nolan's The Dark Knight (2008), the sequel to Batman Begins,[62] before starring in The Edge of Love—about a love quadrangle involving the poet Dylan Thomas—with Keira Knightley, Sienna Miller and Matthew Rhys.

[64] In 2009, Murphy starred opposite rock singer Feist and actor David Fox in The Water, directed by Kevin Drew of Broken Social Scene.

Murphy was attracted to the role as a fan of Broken Social Scene and the prospect of making a silent movie, which he considered to be the "hardest test for any actor".

[65] Murphy also starred in Perrier's Bounty, a crime dramedy from the makers of Intermission, in which he portrayed a petty criminal on the run from a gangster played by Brendan Gleeson.

[67] The direct-to-video psychological thriller Peacock (2010), co-starring Elliot Page, Susan Sarandon and Bill Pullman, starred Murphy as a man with a split personality who fools people into believing he is also his own wife.

[68] Murphy next starred in Christopher Nolan's Inception (2010), playing entrepreneur Robert Fischer, whose mind is infiltrated by DiCaprio's character Cobb to convince him to dissolve his business.

[71][72] Sarah Lyall of the International Herald Tribune described Murphy's character Thomas Magill to be a "complicated mixture of sympathetic and not nice at all – deeply wounded, but with a dangerous, skewed moral code", praising his ability to mimic wickedly.

Lyall noted Murphy's "unusual ability to create and inhabit creepy yet fascinating characters from the big screen to the small stage in the intense one-man show Misterman", and documented that on one evening the "theatre was flooded, not with applause but with silence", eventually culminating in a standing ovation at his powerful performance.

[95] In 2017, Murphy played a shell-shocked army officer who is recovered from a wrecked ship in Christopher Nolan's war film Dunkirk, which emerged as a critical and box-office success.

[115] Reserved and private, Murphy professes a lack of interest in the celebrity scene, finding the red carpet experience "a challenge" that he does not "want to overcome".

[117][118] Murphy's introverted nature and lack of interest in social media has prompted several fans to create memes on his detached demeanour in press interviews and junkets.

In February 2012, he wrote a message of support to the former Vita Cortex workers involved in a sit-in at their plant, congratulating them for "highlighting [what] is hugely important to us all as a nation".