An Enterprise yeoman who is reduced to a small block of chemicals by the Kelvans in 2268 and killed when their leader, Rojan, crushes it as a warning.
Yeoman Leslie Thompson appears in the second-season episode By Any Other Name. She is in the landing party that answers a false distress call and is captured by the Kelvans, visitors from the Andromeda galaxy who mean to take the Enterprise home with them.
After Kirk attempts an escape, Rojan has two of the party, Thompson and the security officer Shea, transformed. Each becomes a pale geometric solid about the size of a fist, holding everything that the person was.
Rojan picks one up and crumbles it in his hand. The other is restored and proves to be Shea. Thompson's death, shown to Kirk as a lesson in obedience, is one of the bleaker moments of the series. She was played by Julie Cobb.