The actor, who played the character on the HBO series since 2011, will appear in new Sky comedy series Two Weeks to Live.
Written by Gaby Hull (Cheat), the six-part series will follow Kim Noakes (Williams), a strange misfit who, after being whisked away to a remote rural life following the death of her father, attempts to assimilate into the real world. Her path soon crosses with two others and, before too long, the trio find themselves on the run from a murderous gangster and the police with a massive bag of stolen cash.
Responding to her casting in the series, Williams said: “Looking forward to getting into something new, I think Two Weeks To Live has really great potential and I want to make something incredible with this wonderful team.”
Two Weeks to Live is the latest in a string of recent commissions from Sky.
Forthcoming releases include Catherine The Great starring Helen Mirren, Code 404 with Stephen Graham and Daniel Mays, Brassic with Michelle Keegan and Hit Men, Mel Giedroyc and Sue Perkins’ first scripted comedy series.
Last week, a Reddit user pointed out that Arya's final scene in Game of Thrones was essentially revealed back in season six.
Game of Thrones is available to view on NOW TV.