A wealthy and feared arms dealer, father of Stella, whose dowry Harry Mudd took before running away and to whom the Discovery crew gladly hand Mudd over in 2256.
Barron Grimes appears at the end of Magic to Make the Sanest Man Go Mad, played by Peter MacNeill. Throughout the episode Mudd uses a time crystal to trap Discovery in a repeating half hour so that he can learn how to sell the ship to the Klingons.
Once Stamets, Burnham and Tyler have outwitted him, they do not send him to prison. Instead they summon the people he has been hiding from: his fiancee Stella and her father. Grimes, it turns out, had put a price on Mudd for absconding with the dowry.
Grimes arrives calm and faintly menacing, assures the officers that Mudd will not trouble Starfleet again, and takes his reluctant future son-in-law away.