The 3ft 8in Glasgow performer has appeared in half a dozen episodes of the cult sci-fi show and even joined the Australian pop icon in the Christmas special three years ago.
He also played a goblin in the first Harry Potter film and is regularly called on for parts in kid’s Doctor Who spin-off, The Sarah Jane Adventures.
But this year he’s back in his home city to play Prof in the King’s panto, Snow White and the Seven Dwarfs, alongside singing star Darius Campbell.
Jimmy, 51, started acting in the 1980s when he went to an open audition for the Ron Howard and George Lucas fantasy film Willow and was cast as stunt double for the lead actor Warwick Davis.
He said: “I auditioned for the part of Willow and I don’t know if Warwick was already cast, but because we looked alike, they said ‘do you want to do stunts?’
“I thought I’d go for it. It was falls, wirework, things like that. It was alright.”
After that Jimmy, who lives in Harthill, ditched his job as a TV repair man, and with the help of Warwick who became his agent, began a new career on the other side of the screen.
He had parts in many TV shows before turning to panto.
He did his first run of Snow White in 1990 and has now been in almost a dozen productions of the classic fairytale.
But he took a big gamble six years ago which propelled him to prime time TV -- and landed him his own dressing room at the King’s.
He said: “I was playing a gargoyle in the TV show Weird Sister.
My prosthetics guy said to me he was doing stuff for Doctor Who, and said ‘there’s a part which will suit you.
“Are you going to be available November and December?’
“I said ‘I usually do panto’, but I cancelled that year and just sat back and waited.
“In December I got a phone call to say I’d got the part in Doctor Who. That was to play a space pig, in series one with Christopher Eccleston.
“It was great.”
Jimmy, who has to buy kids’ clothes to suit his tiny frame, was such a hit in the show that the show’s producers called him back to play more monsters and aliens.
Fans of the show are most likely to remember him as spiky red cyborg Bannakaffalatta who had a crush on Kylie’s character, waitress Astrid, in the episode broadcast on Christmas Day 2007.
Jimmy’s character, which was written specially for him by the show’s creator Russell T Davies, saved The Doctor and Astrid from attack but used up all his power and died in Kylie’s arms.
The show was watched by more than 13 million people, the highest viewing figure for Doctor Who since 1979 and the second most watched show of the year.
Jimmy said: “It was absolutely fabulous that one. Kylie was great -- fantastic to work with. She could take a laugh and a joke like everybody else. She’s down to earth.
“And David Tennant’s a brilliant guy.”
Jimmy has played a variety of other strange creatures in the show and incredibly has worked with all three of the new Doctors - Christopher Eccleston, David Tennant and Matt Smith.
He was transformed into the strange blue goblin-like Moxx of Balhoon in another episode starring Eccleston as The Doctor as well as Billie Piper as his sidekick Rose.
He also became one of the show’s most popular baddies, The Slitheen, in episodes with Tennant.
He also appeared at the Doctor Who Prom in 2008 at the Royal Albert Hall as a character called the Graske.
Jimmy was also part of TV history in David Tennant’s farewell episode, again as The Graske, appearing in a space bar where The Doctor bids farewell to Captain Jack.
And Jimmy’s going back to Doctor Who, which is filmed in Cardiff, next near -- but details of who or what he’s playing are top secret.
Jimmy, who is divorced and has three daughters, says he didn’t even realise he was a dwarf until he saw another one in Blackpool when he was about 21.
When he was born, Jimmy’s parents were told he was going to be “smaller than normal,” but he says he lived a normal life and was never teased by kids at Calderhead Secondary in Airdrie.
Jimmy, who has two sisters who are normal height, said: “I didn’t see a dwarf or a small person until I was 21.
“Nobody ever called me a dwarf. I just got ‘alright wee man.”
Snow White is at the King’s Theatre until January 9.