At one point Dunn was considered by Gene Roddenberry for the part of Spock in The Cage. He was also originally considered for the role of Balok in The Corbomite Maneuver, but that part eventually went to Clint Howard. (source: These Are the Voyages)

Me, I really enjoyed Michael’s work on this ep, as well as on Wild, Wild West, in which he evidently appeared ten times across four seasons!

In his lone appearance on Star Trek, he played Alexander to perfection, a chronically-abused ‘runt-of-the-litter’ who famously turns the tables on his abusers.

https://en.wikipedia.org/wiki/Michael_Dunn_(actor)

Sadly, he seems to have lived in constant pain across his life due to physical problems, ones which ultimately killed him at 38yo. This dude was an absolute boss as I reckon it.