Barnhart was a crewman aboard the starship Enterprise. In 2265, Crewman Barnhart was killed on deck 9 of that vessel by the M-113 creature. (TOS:"The Man Trap").
- Barnhart died wearing the rarely seen Starfleet utility vest uniform, and was carrying his headgear. Some theorize he could have been wearing radiation protection or involved in extravehicular activity or a flight crew, but there is no evidence to support this.
- Barnhart is one of many Enterprise crewmembers to perish in the line of duty. For more, see the list of Starfleet casualties.
- Barnhart was played by Budd Albright, who would later portray Lt. Rayburn, killed by Ruk in "What Are Little Girls Made Of?"