Barnhart was a crewman aboard the starship Enterprise. In 2266, Crewman Barnhart was killed on deck 9 of that vessel by the M-113 creature. (TOS: "The Man Trap")
- Barnhart was played by actor Budd Albright, and was one of many Enterprise crewmembers to perish in the line of duty. For more, see the starfleet casualties.
- 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.