Williamson, who famously played Barry Evans in the BBC One soap for a decade, joked that the money he could make out of appearing in the sci-fi franchise made it appealing.
Speaking to Digital Spy at the launch of his Daz Cleaner Close TV ad, he said: "I think probably Doctor Who would be my ultimate job. Just so I could go to all of those conventions and keep making lots of money year after year.
"But seriously, I would love to go on the show. I'd like to play a villain. It could be me, but just with an extra head."
Williamson also hinted that he could be tempted into a reality TV stint in the near future, admitting that he had held talks with I'm a Celebrity when he left EastEnders eight years ago.
"I think out of all of them I wouldn't mind doing the jungle because it's a great experience they go through. Rather than sitting in a house in Elstree in Borehamwood. In the jungle you would be doing really rather fun things and it's in Australia, I'd love to do that," he said.
"You get to stay there a bit, like when you get a well-paid panto you sign up for two weeks and get put in fabulous hotels."
One reality show he did rule out was Dancing on Ice, claiming that he would be "worse than Todd Carty" if he was asked to perform.
See Shaun take part in the 'Dazathlon' at facebook.com/dazsoapclub and spot the missing trophies to be in with a chance to win a cash prize!