Chris Pratt Reveals Arnold Schwarzenegger's Cute Grandpa Name, Reacts to His Praise (Exclusive)

Schwarzenegger recently shared love for Pratt's new Marvel film, 'Guardians of the Galaxy Vol. 3.'

Chris Pratt is sharing the grandpa name his famous father-in-law, Arnold Schwarzenegger, goes by.

The 43-year-old Marvel star is dad to 2-year-old Lyla and almost 1-year-old daughter Eloise with wife Katherine Schwarzenegger. He also has a 10-year-old son, Jack, with his ex-wife, Anna Faris.

Pratt spoke with ET at the New York premiere of his film, Guardians of the Galaxy: Vol. 3, on Wednesday night, where he opened up about Arnold's praise for the new film and shared the Terminator star's grandpa name.

"Isn't that so nice? Arnold, Opa, Arnold we call him, he came to the premiere," Pratt told ET. "And yeah, he was so nice to give me love and support on his social media. He really liked the movie."

Opa is a common German nickname for a grandfather. Arnold is Austrian-American. Pratt thinks his famous father-in-law is genuine with his praise.

"I think he'd be honest with me. If he didn't like it, I don't think he would post it," Pratt said.

Last month, Arnold took to Twitter to praise his son-in-law's newest project, writing, "WOW @prattprattpratt you crushed it. A non-stop, perfect mix of comedy and action. I loved it and I'm very, very proud of you." 

Pratt also shared his love of Arnold earlier this month during an appearance on Late Night With Seth Meyers.

"I've gotten obviously to know him now as just a regular guy and all of that," Pratt said of Arnold. "He's a great grandfather, a great dad, and a good father-in-law and he's got a wealth of experience, oddly, in the world of promoting blockbuster action movies. It's like, who else are you gonna talk to about that kinda stuff? So that's pretty cool."

Guardians of the Galaxy: Vol. 3 is in theaters May 5.