J. Agalsoff, Jr. 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 2154, he was listed as a member of the Flight Test Crew on the dedication plaque of the Columbia NX-02. (ENT: "Affliction", dedication plaque)

In January of 2155, he was listed as a Trajectory officer on directory placards at Starfleet Command's Fleet Operations Center, Sol Sector. His office was located in room #3480. (ENT: "Demons", directories)

This character was only mentioned in writing.
He was named after sound department member John Agalsoff.