Seth MacFarlane, Sienna Miller join Showtime's Roger Ailes limited series

Seth MacFarlane, who earlier this year expressed how "embarrassed" he felt to be working for a company connected to Fox News, is now among the latest names to join Showtime's limited series about Fox News founder Roger Ailes.

MacFarlane will play Ailes' closest confidante Brian Lewis, the Fox News' public relations chief of more than 17 years who "spent his career promoting and protecting Ailes until the media machine turned against Lewis and ended his career," according to Showtime.

The untitled series is based on the Gabriel Sherman-reported book The Loudest Voice in the Room and stars Russell Crowe in the lead role of Ailes.

MacFarlane joins newly cast Sienna Miller as Ailes ex-wife Elizabeth "Beth" Ailes, Simon McBurney as Fox News cofounder Rupert Murdoch, and Annabelle Wallis as Fox News executive Laurie Luhn who "began a long abusive relationship with [Ailes] that impacted the rest of her life."

"Very excited to be part of this series – loved the book, and it's nice to get off the spaceship now and then," MacFarlane, who created and stars on Fox's The Orville, tweeted.

Back in June, MacFarlane went off on Fox News after personality Tucker Carlson told his viewers to "always assume the opposite of whatever they're telling you on the big news stations."

"In other words, don't think critically, don't consult multiple news sources, and in general, don't use your brain. Just blindly obey Fox News," MacFarlane, who retains an overall deal with 20th Century Fox TV, tweeted. "This is fringe s—, and it's business like this that makes me embarrassed to work for this company."

With Disney's acquisition of Fox assets, Fox TV will move under the Mouse House umbrella and no longer be a sibling entity to Fox News.

While another Ailes project with John Lithgow playing the conservative media tycoon stalled after indie studio Annapurna dropped the title, production on the eight-episode Showtime series will start next month in New York with Naomi Watts as Gretchen Carlson.

KariSkogland of The Handmaid's Tale will direct the first two episodes of the series, which focuses primarily on the past decade, Ailes becoming the "de facto leader" of the Republican Party, the meeting with Richard Nixon that launched Ailes' political career, and the numerous sexual harassment allegations and settlements that ended Ailes' reign.

Related content:

• Russell Crowe to play Roger Ailes in Showtime series on rise of Fox News
• Naomi Watts to play Gretchen Carlson in Showtime's Roger Ailes series