Byxmyx was an Iotian man of the 22nd century.

Byxmyx served as a Chief Administrator on Sigma Iotia II. He met with Captain Stuart Mann of the USS Horizon when it visited the planet in 2102 SFC (c. 2176), and endeavored to make its crew feel at home. After the two men walked through Byxmyx's garden, and Mann described a formal English garden, Byxmyx uprooted his own garden and laid down a new one just like it, with the closest equivalent Iotian plants.

From the crew's stories of Earth, Byxmyx grew to admire the world. He asked to borrow a number of books from Mann, who agreed and gave them, though he would be unable to return to collect them.

Mann found Byxmyx to be quite friendly and amusing. During their acquaintance, Byxmyx picked up Mann's manner of speaking and his limp. (ST reference: Spaceflight Chronology)