William B. Harrison was the flight officer aboard the SS Beagle in the early 2260s.

When the Beagle was damaged and abandoned in 2262, Harrison was captured, along with the rest of the crew, by the inhabitants of the planet 892-IV and forced to fight as a Roman gladiator.

Harrison was killed in 2268 by a gladiator named Claudius Marcus. His demise was accidentally seen by the crew of the Enterprise via an Empire TV broadcast. He was the last of the surviving Beagle crew, with the exception of Captain R.M. Merik. (TOS: "Bread and Circuses")