How Being “Such a Jerk” Landed Mark O’Brien a Role in The Copenhagen Test
Mark O'Brien, who plays Cobb in the Peacock spy thriller, reveals he worried after auditioning, "I went too heavy on the jerk thing."
Canadian actor Mark O’Brien wasn’t sure about the kind of impression he left after auditioning for Peacock's new spy series, The Copenhagen Test.
But as it turned out, he played the character of Cobb as just the right amount of "jerk." Cobb works for The Orphanage, a U.S. watchdog organization for other American intelligence agencies. He scores a promotion early on in the series, beating out Simu Liu's intelligence analyst Alexander Hale, the espionage thriller's main character who finds out his brain has been hacked by an unknown entity.
The Orphanage and Alexander agree to keep the hack open in order to try to control what the enemy spying through Alexander sees and hears and use it to their advantage, letting only a select few in on this secret. But Cobb, who feels he's a professional rival of Alexander, threatens to expose this since he suspects that Alexander is the mole their organization is looking for.
O'Brien — known for his roles in series like City on a Hill, and in films like Ready or Not — recalled playing the character a bit slimy during the audition process and thinking he went "way too far."
Mark O’Brien played The Copenhagen Test's Cobb as "such a jerk" while auditioning
"I read for them and then I said, 'I just need to just do it again, please,'" O'Brien told Peacock Blog in a December 2025 interview. "I didn't want anyone to say anything to me, I just wanted to do it again. And I was such a jerk that everybody laughed and I wasn't sure if they were laughing at me or at what I was doing, and it turns out it was at what I was doing, in the good way."
He added, "I remember when I left, I was like, 'I went too heavy on the jerk thing' and, 'I went way too far,' but I guess not — because here we are."
Jennifer Yale, a co-showrunner and executive producer of The Copenhagen Test, agreed that O'Brien's ability to play up Cobb's "jerk" side was what helped land him the part.
"Cobb is my favorite character, because he's an a-----e who doesn't know he's an a-----e," Yale said in the show's production notes. “And Mark was incredible. He came in, and all of us just looked at each other and knew he was perfect for the role. He is very charming, but at the same time, you want to slap him. There's so much fun in the dynamic between him and Alexander. He was wonderful at playing the different layers of Cobb, the insecurities that come through, as well as the arrogance. It was fun to write for him, and to watch Mark perform."
The espionage thriller follows Alexander as he tries to figure out who to trust after discovering his brain has been hijacked, giving access to everything he sees and hears to the perpetrators.
While Alexander and Cobb have a respect for each other, Cobb can't help but try to take Alexander down when he believes his colleague is actually a mole.
"That's the fun of the role," O'Brien told Peacock Blog of Cobb. "He's sort of condescending, but kind of can't help it, I think, in a way too. But it's fun to play someone who can tick people off."
Where was Peacock’s The Copenhagen Test filmed?
The Copenhagen Test was filmed in Toronto, Canada, which worked out well for several cast members who had ties to the area. O’Brien was born in the Newfoundland province of Canada and worked in Toronto during the early days of his acting career. Liu, who was born in China but immigrated to Ontario, Canada as a young child, also kickstarted his career in Toronto.
“I lived there for seven years, and I met Simu there years ago and even some of the cast that were coming in, some of the guest stars, like people who I knew or worked with when I was younger, so it was very cool,” O’Brien shared. “Even locations, I was like, ‘God, I think I filmed something here when I was like 20.' All those memories came back and it’s a fun thing when you’ve been doing this long enough that you revisit places or people that you’ve worked with before."
O’Brien remembers calling his wife to rave about his The Copenhagen Test castmates once they started filming the series. The actors often hung out after filming wrapped.
“This was my first time in Canada for the winter, so I was very cold and out of my element,” Sinclair Daniel, who plays Parker on the show, told Peacock Blog. “I think I went out with these people more than I went out when I’m at home. We would have dinners, and game nights, and bowling. It was a lot of fun, especially since we didn’t all get to be on the set at the same time, so still feeling like we were all connected.”
All eight episodes of The Copenhagen Test are now streaming on Peacock.
