A Starfleet commander serving on the bridge of the USS Reliant under Captain Terrell in Star Trek II: The Wrath of Khan, during the survey that leads the ship to Khan.
Beach is a senior officer of the USS Reliant in 2285, seen in Star Trek II: The Wrath of Khan while the ship searches for a lifeless world on which to test the Genesis device.
As the Reliant orbits what its crew believe to be Ceti Alpha VI, Captain Terrell asks Beach whether the surface scan has changed; it has not, and the faint life reading that Chekov has picked up persuades Terrell to beam down with him to investigate, leaving the ship in orbit.
The landing party walks straight into Khan Noonien Singh, who seizes the Reliant and maroons its crew on Ceti Alpha V. Beach is not seen again and presumably shares their fate until the Enterprise returns for them.