The actor, who has played the role of Jamie Fraser in the hit show for the last eight years, revealed he had been in talks about making a stage comeback before the shutdown of theatres by the pandemic.
The 40-year-old, who is currently filming the sixth series of Outlander in Scotland, has also discussed his ambitions to seek out “a real acting challenge” after being cast in action movies in recent years.
Heughan, who told how he spent around 10 months of the year making Outlander, said making films was “like a holiday” in comparison.
Speaking in fellow actor Nicola Roy’s new podcast, The Cultural Coven, Heughan spoke of his affection for Shakespeare and the Royal Lyceum in Edinburgh, where he made his first stage appearances after joining its youth theatre group.
Heughan said: "Outlander is the most difficult job I’ve done. I've been lucky to do a couple of movies in the last few years. To be honest, compared to Outlander, they’re like a holiday.
“Outlander is brutal. It’s such a big show, we’re normally filming on location, there are so many moving parts, there is so much hair and make-up for hours before you start production. It’s kind of gruelling.
“We’re not saving lives or working in a hospital, but they are long days and it’s kind of relentless. You need to have a lot of energy, and find levity and lightness when you can.
"It normally takes us around 10 months a year to film each season. It’s not fast. The show is quite epic and filmic. They take their time on the big set-pieces.
“But it’s not like doing a cop show where you’re on the same set every day. Every episode and season feels different. My character has aged as well – from 23 at the start to 50 now.”
Asked in the podcast if he had any concerns about being typecast, Heughan said: “I definitely want to do something else.
“Jamie Fraser has obviously been brilliant and I’ve been doing a number of film roles to try to play other parts, but they’ve all been primarily in the same sort of realm.
“I’d love to have a real acting challenge - I think that’s where you get to really stretch yourself.
“Outlander has been so unique. My character has been a young warrior, who has become a laird, a father, a husband and a grandfather now, he’s been in battles, he’s been abused... I’ve had so much to play.
“But of course we all get burn-out and want to do different things.”
Heughan’s first major role was in the 2002 Traverse Theatre play Outlying Islands.
He added: “I did a lot of theatre when I left drama school. It's eight years, since I started doing Outlander, that I've been doing film and TV.
“I'd love to go back to theatre. I have been talking to various people, before the pandemic.
“It’s about scheduling and that’s kind of tough right now with the film schedule I’ve got, but in the future, I’d love to.
“For me, it’s always been about Shakespeare. I’d love to do Hamlet, Romeo and Juliet, and Macbeth.”