Fisher (Technician)

From Memory Alpha, the free Star Trek reference.

Fisher was a geological technician aboard USS Enterprise. He was injured during a geological survey on Alfa 177 after slipping down a rock, during which he smeared his uniform with a strange magnetic ore. He was subsequently beamed back up to the Enterprise. Unfortunately, the ore corrupted the transporter system and caused Captain Kirk, who beamed up immediately afterwards, to be split in two: one good Kirk and one evil Kirk. Several hours later, he found the evil Kirk attempting to rape Yeoman Janice Rand. He then tried to contact Spock, but was assaulted by the evil Kirk before he could do so. (TOS: "The Enemy Within")

Fisher was played by Ed Madden. Madden also played a geologist in TOS: "The Cage", which takes place in 2254, approximately a dozen years before his appearance as Fisher. It seems unlikely the creators could have intended this to be the same man, as there would presumably be some changes in appearance over a decade of time.