An Enterprise engineering ensign who is vaporised in 2268 when the experimental M-5 computer draws power directly from the warp engines as he tries to disconnect it.
Ensign Harper appears in the second-season episode The Ultimate Computer. The M-5 multitronic unit, designed by Dr Richard Daystrom, has been installed to run the Enterprise through a series of war games with only a skeleton crew aboard.
After M-5 destroys an unmanned ore freighter, Kirk orders it shut down. The machine protects itself with a force field, so Scott sets Harper to pull its main power connection by hand.
As Harper reaches for the junction, M-5 throws out a beam of energy to tap the engines for itself, and he is caught in it and killed. Daystrom insists that it was an accident. The death is the first real proof that the computer will put its own survival above human life.