A Newfoundland-born boy battling cancer is being hailed on Facebook as "the funniest, potty-mouthed Canadian mercenary" Ryan Reynolds has ever met. 

The Canadian actor took to Facebook Friday afternoon to share a photo of himself with Connor McGrath β€” and encourage people to donate to McGrath's cause.

The 13-year-old has been fighting acute lymphoblastic leukemia since age 10.

Family and friends of the McGraths, who now live in Alberta, have been trying to raise enough money to send Connor to the United States for an experimental cancer treatment. 

Reynolds said McGrath is "quite possibly the biggest Deadpool fan on Earth."

That's high praise, considering Reynolds is the star and one of the producers behind the R-rated super hero film β€” which is already estimated to bring in a whopping $130 million at the box office during its opening weekend. 

​In his post, Reynolds revealed that he gave McGrath a private, hospital room screening nearly two months ago.  

"He was ... the first person ever to see the Deadpool film. Like Wade Wilson, Connor's trying to put cancer in his rearview mirror," Reynolds wrote, comparing the teen to the film's main character. 

And much like his colourful character, dubbed the Merc with the mouth, Reynolds didn't hold back. 

"Holy ... I love this kid. He is the greatest. And he needs your help to get well."

Supporters have started a YouCaring campaign, with the hope of raising $800,000. The money will go towards a costly therapy treatment in Philadelphia. 

Reynolds said that he's donated money to the cause and encouraged others to do the same.