The Gossip Girl actor will play TJ, the troubled sibling of the Happy Endings star's character Douglas, in the USA network's upcoming drama.
© PA Images / Jennifer Graylock/AP
© PA Images
Stan's alter-ego is described by TV Line as "a lost soul struggling with addiction", the polar opposite of his "perfect" brother.
The six-part series is set in Washington DC and centres around a former First Lady's family headed by Sigourney Weaver's character Elaine.
Political Animals is the latest project from Greg Berlanti of Dirty Sexy Money and Jerry Maguire's Laurence Mark.
It is due to debut in the summer.
