P. Baillargeon was a Human Starfleet officer in the 22nd century.
In January of 2155, he was listed as an Orbital Mechanics officer on one of the directory placards at Starfleet Command's Fleet Operations Center, Sol Sector. His office was located in room #4238. (ENT: "Demons", United Earth directory)
This character was only mentioned in writing.
He was named after Enterprise composer Paul Baillargeon, who also composed music for Star Trek: Deep Space Nine and Star Trek: Voyager.