Lieutenant DeSalle was a 23rd century command division Starfleet officer who served at times as both the assistant chief engineer and navigator aboard the USS Enterprise under Captain James T. Kirk
during the mid-2260s. DeSalle was of French descent and trained in many skills, including biology.
In 2267, on stardate 2124, DeSalle was one of three people who beamed down to the planet Gothos in search of Captain Kirk and Lieutenant Sulu
, who had been abducted by the powerful alien Trelane. Expecting to arrive in an inhospitable climate, this landing party was surprised to discover an oasis of Earth-like conditions. When communications failed, DeSalle attempted to contact the ship using a laser beacon, but this method also failed. DeSalle later attempted to shoot Trelane with his phaser, an act that resulted in his paralysis, and the theft of his weapon by Trelane, who delightedly experimented with it, disintegrating several of his bizarre trophies before returning the weapon.
Later that year, on stardate 3417, DeSalle accompanied Captain Kirk on a landing party to the Omicron colony on Omicron Ceti III. DeSalle discovered that, anomalously, the colonists themselves had been the only animal beings to survive exposure to the planet's berthold rays. He also performed an analysis on the crops grown by the colonists. Like the rest of the Enterprise crew, DeSalle fell under the influence of the Omicron spores and mutinied, though he later recovered thanks to a subsonic transmitter.
On stardate 3018, DeSalle was placed in command of the Enterprise while the rest of the command staff (including the captain, first officer, chief engineer and the helmsman) were off the ship, and spearheaded an effort to pierce the alien barrier erected by Korob to prevent the Enterprise from sending help to the landing party trapped on Pyris VII. The Enterprise crew were close to escaping the field when Korob removed it himself, as part of his effort to help the Starfleet explorers escape Sylvia's attention.