The 54-year-old is well-known for his flamboyance and humour, but has apologised for “tomfoolery,” after it emerged he had revealed himself to crew on Doctor Who and Torchwood.
Barrowman co-starred alongside actor Noel Clarke - who is currently facing sexual misconduct allegations of his own - and it was Clarke who commented on Barrowman’s behaviour back in 2015.
So, what has he been accused of and how has Barrowman responded to the backlash? This is what you need to know.
What is John Barrowman accused of?
In a resurfaced interview from 2015, Clarke remarked that Barrowman would expose his genitals "every five seconds" while "hitting it on everything".
Barrowman has not denied the claims, which were made in jest and not in relation to sexual harassment.
It has now been reported that his career could hang in the balance, as producers and commissioners are taking a no nonsense approach to dealing with behaviour which could be seen as sexually overt and unwanted.
The six year old clip has reemerged after allegations against Clarke led to spotlight on sexual harassment and misconduct in the workplace.
Clarke currently faces around 20 accusations of sexual harassment and bullying, which bosses of the BAFTA awards were aware of before handing him the ‘Outstanding British Contribution to Cinema’ award on 10 April.
The women who have accused Clarke have now spoken out anonymously, leading to him being strippped of his BAFTA and various roles in TV dramas and films until the investigation is complete.
How has Barrowman responded to comments about his conduct?
The Doctor Who star has taken to Twitter to speak out about the backlash and how he feels about it.
He thanked his “fan family” for supporting him and said he has previously apologised for any unintended discomfort he caused those around him.
On 1 June, he posted a video to his 521,000 Twitter followers, in which he said "Hi everybody, it's John here and I just want to say thank you very much to all of my fan family and everybody who has reached out with the countless messages of support over the last few weeks.
"It has meant such a great deal to me and has really touched me to know that people are supporting me and standing by me and sending their love and all of their appreciation and kind words."
Barrowman added: "Hopefully we will all be back together some time soon and I look forward to it. Much love and thank you."
He also addressed his behaviour when the clip resurfaced last month.
Barrowman said his "high-spirited behaviour" was "only ever intended in good humour to entertain colleagues on set and backstage".
He added: "With the benefit of hindsight, I understand that upset may have been caused by my exuberant behaviour and I have apologised for this previously.”
His husband, Scott Gill, also thanked fans for their support.
On 1 June, Gill wrote on Twitter: “It’s been a ‘challenging' 3 weeks for both of us, watching
@JohnBarrowman get hounded in the press & viciously attacked by trolls, but mostly it’s been amazing how many wonderful people have rallied around in support. To all of you who have sent us lovely messages - THANK YOU!”
At present, there have been no complaints brought to light over his behaviour on any film or TV set.
Has he been penalised by his employers?
Since the backlash began in May, Barrowman, known for playing Captain Jack Harkness in Torchwood and Doctor Who, has been removed from an interactive exhibit about the show.
It is also thought his judging career on ITV’s Dancing on Ice is in question, though no official comments have been made.