(covers information from several alternate timelines)
Michael "Mike" Westmore was a Starfleet officer who served during the mid-24th century.
In 2328, Westmore was listed as a commercial transport passenger aboard the SS Kogin, where he was ferried with his traveling companion, Marion Westmore, from Earth Colony II to the Tellun system.
His passenger manifest was accessed by Lieutenant Commander Data aboard the USS Enterprise-D in 2370 by reviewing this data in the commercial transport database. (TNG: "Inheritance", okudagram)
According to the dedication plaques of various Federation starships, Westmore was listed as a yard engineer during the construction of the USS Defiant at Antares Ship Yards in 2370, USS Voyager at Earth Station McKinley in 2371, USS Valiant, again, at Antares Ship Yards in 2372, USS Prometheus at Beta Antares Ship Yards in 2374, and USS Sao Paulo at Utopia Planitia Ship Yards in 2375. (DS9: "The Die is Cast", dedication plaque; VOY: "Caretaker", dedication plaque; DS9: "Valiant", dedication plaque; VOY: "Message in a Bottle", dedication plaque; DS9: "The Dogs of War", dedication plaque)
During this time, as well in 2372, he was named as member of the Propulsion Systems team at San Francisco Yards, listed on the dedication plaque of the USS Enterprise-E. (Star Trek: First Contact, dedication plaque)
In an unknown, alternate future timeframe, he was named as a member of the Fleet Ops team at the Marin County Starfleet Yards, Skywalker Division, listed on the dedication plaque of the USS Pasteur. (TNG: "All Good Things...", dedication plaque)
This character was only mentioned in writing.
He was named after makeup artist Michael Westmore.