Captain John Whorfin was the commanding officer of the 22nd century Earth starship SS Buckaroo Banzai. He commanded the vessel during its 2137 mission to Planet 10 (DIM-8). (TNG: "Up the Long Ladder")
Background
The name of this individual appeared on an Okudagram that appeared on Picard's desk monitor, and was not verbally referenced on screen. A legible version of the Okudagram would appear in the reference book, Star Trek: The Next Generation - The Continuing Mission.
This reference was an in-joke to John Lithgow's character in the cult science fiction adventure The Adventures of Buckaroo Banzai Across the 8th Dimension.