EXCLUSIVE: Katie Holmes, Matthew Perry on Playing Kennedys in 'After Camelot' -- See What They Said

The upcoming Reelz miniseries explores the iconic family's tragic story.

Portraying such a well known historical figure has its challenges.

Nonetheless, it's a task Katie Holmes and Matthew Perry decided to take on in the upcoming Reelz miniseries, The Kennedys: After Camelot, which is expected to premiere later this year.

The co-stars sat down with ET's Leanna Aguilera at the Television Critics Association press tour in Pasadena, California, on Friday, where they shed some light on how they got into their respective roles -- Holmes as Jacqueline Kennedy Onassis, and Perry as Ted Kennedy.

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"It was really an honor to play her," Holmes shared of taking on the iconic role. "Watching Jackie go through the loss of Bobby, then falling in love with Onassis, marrying him, the demise of that relationship, returning to New York, working at Doubleday, and in the midst of all attention publicly. Raising her children the best that she can ... I'm proud that we have this very famous family, but I think we're telling very human stories."

This is actually Holmes' second time portraying Jackie O., but for co-star Perry, the experience is a new one.

WATCH: Katie Holmes Giddily Channels Jackie O. On Set of 'The Kennedys: After Camelot'

"I've never played somebody who really exists before, so that was fun," the 47-year-old actor shared. "Learning the accent, and wearing prosthetic ears, and prosthetic nose ... I played him from [age] 38 to 67, and sometimes in the same day I'd switch over."

And the constant prosthetic and body changes for Perry became a real issue when the actor was tasked with playing Ted at times when the politician was smaller than the actor is in real life.

FIRST LOOK: Katie Holmes and Matthew Perry Dive Further Into the Kennedys' Tragedies in 'After Camelot'

"During the Chappaquiddick time, he had more of a stocky, thinner build than myself," he explained. "So, they created a compression suit for me, which I had to wear and in which I could not move ... If I had to go to the bathroom it was an hour and a half ordeal."

"So he didn't have any liquids," Holmes added.

Perry continued, "Halfway through, I went, 'Someone take that compression suit and throw it in the garbage!' 'Cause I'm not wearing that anymore."

Thankfully, it was all worth it for the Friends alum.

"It was a really challenging role, which is what I was expecting it to be, and what I was hoping it would be, so it was a really good challenge," he noted. "Actors live for good writing, and being able to play good parts, and this certainly is both."

PICS: Katie Holmes Glows as Jackie Kennedy in Her Wedding Dress in 'The Kennedys: After Camelot'

Meanwhile, Holmes also opened up about her cameo in the upcoming Ocean's 8 film.

Watch the video below.