Les Earnest
The Stanford administrator who wrote finger so nobody had to walk the halls looking for people — and who had built one of the first spell checkers years earlier.
Lester Earnest started at MIT Lincoln Laboratory, working on the SAGE air defence system. In the early 1960s he built a program to recognise cursive handwriting, and to make it work it needed a word list to check against — an early spell checker. In 1965 he became executive officer of the Stanford AI Lab, SAIL, where he stayed for many years.
At SAIL around 1971 he wrote finger, because colleagues wanted to know who was at the terminals without wandering the building. The program became an internet protocol, and the .plan files it displayed became an early kind of status update. That it also handed out usernames to anyone on the network was a problem nobody worried about until much later.