Picking a best XI of players he played with is an extremely tough task.
He had a go at doing just that on a documentary with Patrick Vieira in 2013, titled: "Keane and Vieira: Best of Enemies".
Keane was his usual brutal self as he made a number of controversial choices.
View his XI below... (from 12:02)
GK: Peter Schmeichel
RB: Paul Parker
CB: Jaap Stam
CB: Gary Pallister
LB: Denis Irwin
RM: David Beckham
CM: Roy Keane
CM: Paul Ince
LM: Cristiano Ronaldo
ST: Eric Cantona
ST: Ruud van Nistelrooy
Keane did at least say that Neville would have made the bench.
Vieira was particularly surprised upon hearing that Paul Scholes did not make the XI.
When asked which player he would have included, the Frenchman said: "Scholes [should have been included], no doubt about it. I think Scholes was, for me, the best English player and one of the best United players that I played against. He can do everything."
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Explaining his decisions, Keane said: "Having a great career doesn't mean you are a great player - there's a big difference. I'm not saying Giggsy wasn't (great), but do I leave out Ronaldo, one of the world's great players? Do I leave Becks out?"
"You don't win titles by having choirboys in your dressing room."
Scholes was asked about Keane's XI a few years later but he did not have any hard feelings at all.
Scholes said, per the Mirror: "When people name teams, it's a matter of opinion. Me and [David] Maysy could sit here all day and pick 10 different teams, the amount of brilliant players that played here, so I wasn't bothered by it. I'm still not bothered by it."