G. Tachell was a Human Starfleet officer in the 22nd century.

In 2151, he was listed as an Imaging and Sensor Technologies officer on the dedication plaque of Enterprise NX-01. (ENT: "Broken Bow", dedication plaque)

In January of 2155, he was listed as an ODIN officer on the directory placards at Starfleet Command's Fleet Operations Center, Sol Sector. His office was located in room #1323. (ENT: "Demons", directories)

This character was only mentioned in writing.
He was named after ENT camera operator Gary Tachell.