Kelsey Grammer cast as the villain in Transformers 4

The Autobots have gone up against Megatron. They've gone up against The Fallen (and Megatron), and they've gone up against Sentinel Prime (and Megatron). Now they're set to face their gravest threat yet, with Deadline revealing that director Michael Bay has found his baddie for the fourth instalment in the Transformers franchise. No, it's not Unicron (not yet, at least) - it's Frasier and X-Men: The Last Stand star Kelsey Grammer, who has signed on to play Harold Attinger, a human villain described as "a counter intelligence guy." Based on past form, he's probably in league with Megatron.

Transformers 4 is set to take place four years after the events of Transformers: Dark of the Moon, and is intended as a "revamp" of the blockbuster movie franchise. Bay has jettisoned the entire cast of the original Transformers trilogy, with his Pain & Gain star Mark Wahlberg set to lead a new line-up of humans alongside Stanley Tucci (Captain America: The First Avenger), Jack Reynor (What Richard Did) and Nicola Peltz (Bates Motel). They'll be joined by four winners of the creatively-titled Chinese talent show Transformers 4 Chinese Actor Talent Search, while Peter Cullen will return to lend his voice to Autobot leader Optimus Prime.

Filming on Transformers 4 will get underway this summer in Chicago, with the sequel currently slated to arrive in cinemas on June 27th 2014, just weeks after the arrival of the Bay-produced live-action Teenage Mutant Ninja Turtles reboot.