Lieutenant Simmerith was a male Chelon Starfleet officer serving in the late 24th century.
By 2381, Simmerith had been assigned to the USS Aventine as a security officer. During the Borg Invasion of 2381, the Aventine and the USS Enterprise-E traveled through a subspace tunnel from the Azure Nebula, hoping to find the staging area of the Borg, but ended up near the Carina Arm near the border of the Delta and Gamma Quadrants. A fleet of Hirogen vessels attacked and boarded the two vessels, and Simmerith was one of the officers to attempt to defend Main Engineering from the Hirogen hunters. Although Alpha Hirogen Ormoch impaled Simmerith with his sword, killing him, he was able to strike the final blow with his claw, infecting Ormoch with his natural toxic secretions.