M. O'Halloran was a member of Starfleet in the 22nd century.
In January of 2155, O'Halloran worked in OSO at the Fleet Operations Center on Earth. O'Halloran's office was located in room 4237. (ENT: "Demons" set artwork)
O'Halloran's name was seen on directory listings seen on the set of "Demons".
M. O'Halloran was named after Enterprise assistant editor Michael O'Halloran.