The bitter rivalry began in earnest in 2010 when, barely six months after replacing Leno as host of 'The Tonight Show', Conan was ousted from the show.
Conan told ShortList magazine: ''In some ways, that was more intense than Jay versus Dave [Letterman].
''It felt like the younger guard [supporting Conan] against the old guard [Leno]. People were having rallies, making videos slamming NBC, and NBC was thinking, 'How is Conan doing this?'
''I was being credited as a genius when I didn't have the slightest idea who these people were.''
Conan - who now hosts a new self-titled talk show - added that some of his most ardent fans even went so far as to get a tattoo as a show of support. He was, however, quick to point out that he didn't necessarily appreciate the gesture.
The talk show host added: ''They've tattooed my face on their body. I always feel like, 'Look, I'll pay to have that removed.' ''
'Conan' will begin airing in the UK on TruTV, Mondays to Thursdays at 11pm, from August 4.
He also slapped a jet-lagged Taylor Hawkins.
The acclaimed performer had just cancelled touring due to a battle with cancer.