Leonard Nimoy has joined the cast of Transformers: Dark of the Moon. He’s been hired to provide the voice of Sentinel Prime, Optimus Prime’s predecessor as leader of the Autobots. That’s the transformer we saw in the Dark of the Moon teaser trailer, hanging out on the moon and looking none too happy about it.

According to EW the character will play a pivotal role in the new Transformers story, eventually coming to Earth where he’ll disguise himself a fire engine and take part in the movie’s big, final battle in Chicago.

For his part Nimoy has been interested in getting involved in the Transformers franchise for awhile. Back in 2009 he was rumored to be lobbying for a robot voice in Revenge of the Fallen. Aside from that he already has a long history with the world of Transformers. If you saw Transformers: The Movie back in 1986, that was his voice you heard coming out of the mouth of Galvatron. Plus, he’s married to Michael Bay’s cousin. No really, Susan Bay is his Nimoy’s wife.

For my part I remain slightly baffled that Leonard would come out of retirement for something so minor. After his appearance in the last Star Trek he made it pretty clear that he was headed for retirement. These days Nimoy is more interested in taking photos than he is in acting. Perhaps playing the voice of a giant robot doesn’t really count. It’s good to have him back on screen, in any capacity.