The Edinburgh author says the grizzled detective will never be “bumped off” in future novels, even though he has warned fans that he likely to stop writing about him soon.
He has decided against writing a new Rebus thriller next year - despite plans to celebrate the 30th anniversary of the celebrated detective.
When he appeared at the Edinburgh International Book Festival in August, Rankin admitted “the clock is ticking big time” for Rebus.
Speaking in a new BBC Scotland programme, Rankin said is likely to decide there will come a time for the character when he decides “enough is enough.”
Rankin was asked about Rebus by two former real-life detectives Tom Wood and Peter Ritchie for the Radio Scotland show Good Cop, Bad Cop, which is broadcast tomorrow.
Asked by Mr Wood why he is not prepared to “let him go,” the writer said: “I cannot imagine bumping him off. I cannot imagine killing him off. I can imagine an end point where enough is enough.
“He’s not going to become a cab driver, he’s not going to open a B&B in Marbella, he’s not going to do the things that retired detectives ought to be doing. He’s a cop. He’s a detective to the very core of his being. If he ceases to be a detective then he ceases to be. The only thing waiting for him is a protracted slow death, sitting in the pub all day, drinking whisky and chasers.
“He needs the work and needs to feel useful. He uses police work and detection as a way of not looking at all the problems in his own personal life. He’s looking at other people’s problems. He’s a professional voyeur, as many detectives, and all authors, are.
“I only do it one book at a time. As I sit here, I’ve no idea if there will be a book after that. If there is, will there be a Rebus, and if it is, will it be the last? I just don’t now.”
Rebus appeared to have work on his final case in 2007 in the novel 2007, which was set during his final days as a working detective.
But the character has been called out of retirement four times since then by Rankin, including the forthcoming new novel Rather Be The Devil, which sees Rebus face up to arch-nemesis “Big Ger” Cafferty once again.
Rankin added: “It’s Rebus who won’t let go. He refuses to leave the building. There’s still a bit of life left in the old dog. He’s still an engaging character for me to write about.
“I’m still finding things out about him. I’ve written 20 novels about him, he’s been in my head since around 1985, but I’m still finding out fresh stuff about him, and still trying to make sense of his world and what makes him tick.”