Whether he is in or out of a job, Roy Keane never appears to be far from the headlines.
Since retiring from the sport in 2006, having also had a spell with boyhood club Celtic, he has appeared as an assistant boss to O’Neill but also spent time in management with Sunderland and Ipswich.
On Sunday, he quit his role as O’Neill’s assistant at the City Ground, reportedly with an eye on returning to management in his own right.
But how much is the 47-year-old worth?
What is Roy Keane's net worth?
Keane’s wealth is difficult to estimate, but the former Ireland star has not made the latest edition of the Sunday Times Rich List, meaning that it is very probably below €57 million (£51m/$65m). Indeed, most estimates place his fortune between €40-€45m.
How much did Roy Keane earn with Man Utd?
When Keane signed for Manchester United for £3.75m in 1993, he moved for a British record transfer fee. At the time, he was paid a wage £350,000 a year – a figure that many modern-day players are now paid in a week.
His growing influence at United, as well as the explosion of the football market, meant that his wage would ultimately spiral to £90,000 per week when he left the club in 2005 to join Celtic.
He moved to Parkhead to play for the club he supported during his childhood and took a dramatic wage cut there, earning only £20,000 per week.
What did Roy Keane say on modern transfer fees?
Keane has been outspoken on the amount of money floating about in the contemporary game and has been especially critical of the giant transfer fees that have become normalised.
“It's mind-boggling, the figures that are out there - especially for the average players,” he told The Telegraph in 2017. “If ever there was a time to be a professional player it's now. Average players are going for £35 million. My goodness.
“I don't really analyse it too much, but that's the market place at the moment. There aren't many top players out there. The really big players are going for big money and it's filtering down now.
“When average players are going for £30-40m, it does make you scratch your head, but if the clubs are prepared to pay that, then it's not the players' fault.”
Later asked what his former Manchester United team-mates would be worth in the current climate, he replied: “Ruud van Nistelrooy would be worth in the market now probably £1bn. David Beckham? £1bn. Ryan Giggs? £2bn. Keane? £3.75m.”
What charity work does Roy Keane do?
Although he has a hard-man reputation, Keane is well renowned for his charity work, particularly in Ireland.
He has been a particularly strong patron of Irish Guide Dogs and has regularly appeared in adverts for the charity over the years.
“He’s been amazing for us,” founder Jim Dennehy told the Irish Times in 2018.
“When he’s home in Cork he’ll always make time to come up to us and spend time with the dogs and with the staff. He really understands what we do and believes in it.
"We couldn’t have asked for a better person to be our ambassador. Like Roy always gives us a shout-out where he can. We appreciate that so much, he’s a great man.”
Keane also played a highly instrumental role in arranging a tribute match for former Manchester United team-mate Liam Miller, who died of pancreatic cancer in 2018.
He successfully rallied a crowd of 45,000 to turn out in Cork to raise funds for the late player’s family and to support the Marymount Hospice.
“It was great, a really nice day. Great for Liam and his family that they got a great turnout," Keane said of the event.
"There was a great atmosphere, there was a real good buzz in the city and people have done great work to make this happen. I'm really proud of the people that made the effort."
He has also taken part in Soccer Aid, playing for the Rest of the World team in the 2012 edition.
The Rest of the World team lost 3-1 to England, but Keane's involvement ended after 23 minutes - with his team 1-0 up.
"That's Roy Keane," said X-Men actor and team-mate in the event James McAvoy when he met the Irishman at training. "Giving everybody a bit of attitude. That's what this dressing room needs - a bit of a kick up the you-know-what!"