David Mackenzie is the author (or co-author) of many basic GNU utilities such as `ls`, `chmod`, `touch`, and many others. I was looking up the manpage for the `install` command today and came across his name listed as its sole author. I had some time to kill, so I looked him up and this fascinating video came up in which he discusses his early life and how he came to work for GNU and wrote all these utilities. I highly recommend watching this till the end.