Thorvald Pearson was a male in Starfleet in the 23rd century. In the late 2260s, he held the rank of lieutenant, and was assigned as head of stellar cartography aboard the USS Enterprise. During this period, he commanded a shuttle mission to planet Algenib II. His shuttle crashed on the planet, and he and his landing party went missing. (TOS - Constellations short story: "Make-Believe") The ultimate fate of Pearson and his team was not revealed in the story.