Caitriona Balfe has been praised by both critics and fans for her portrayal of Claire Randall/Fraser in the historical fantasy drama series, Outlander. It is difficult to imagine the character being portrayed by someone else. But not known to many, there was another actress who was also favored to play the role. 

About 10 years ago, Diana Gabaldon's novel was originally planned to be adapted in a feature-length movie rather than a TV series. At the time, it was reported that the producers of the supposed film wanted Grey's Anatomy alum Katherine Heigl to play the role of Claire, a former World War II nurse who traveled to the past and fell in love and eventually married a Highlander.

In a previous interview with The New York Times, Heigl hinted that she was seriously considering taking the role. She asked the publication, "Scotland? 2012? What do you think?"

Heigl just starred in some hit films such as Knocked Up, 27 Dresses, and The Ugly Truth. Apparently, this made her one of the highly sought after actresses at the time. 

But then, the film adaptation was changed into a TV series that Starz commissioned. From there, it looks like the TV series creators decided to take a different route when it comes to the lead female character. 

Outlander showrunner Ronald D Moore earlier shared with Collider how they thought Claire would be the easiest character to cast. Claire's description was pretty straightforward. She is a smart 20th-century British woman and they are confident that there are many actresses who could play the role. 

But it turned out that they had a hard time finding the right actress for the role, leaving them to cast the character last. Moore admitted that casting Clare was tricky because they tried to find a very special trait of an actress who could work really well with Heughan. The Bloodshot actor was the first to have been cast which means his supposed love interest should show a spot on chemistry with him. 

Moore revealed that they watched tapes of several actresses before they found Balfe. Just before production began, they saw the Ford vs Ferrari actress' audition tape and they asked her to come in for a screen test with Heughan.

Moore revealed in Outlander Season 3 Collector's Edition Blu-ray that the screen test with Heughan was the final test before they decide if the role of Claire was meant for Balfe. Although they are confident Balfe can deliver based on her audition tape, they still have to see the right emotional connection between the two stars. 

After the screen test, the camera kept rolling to see how Heughan and Balfe interact with each other. Moore said what they saw was a "genuine affection" between the two.