- William Kasozi
- William Kay
- William Keesler
- William Keleher
- William Keniry
- William Kennard
- William Kennedy
- William Kerganevet
- William Kerr
- William Kessinger
- William Kidd
- William Kilmer
- William Kindorf
- William King
- William Klein
- William Klein
- William Klima
- William Klitgaard
- William Kloos
- William Koenig
- William Kolb
- William Kolibash
- William Komaroff
- William Kowals
- William Kraus
- William Kremer
- William Kridel, Jr
- William Kridel, Jr.
- William Kuhlman
- William Kummerer
- William Kuntz
- William Laboratories Acquired By Temptime
- William Lafferty
- William Landman
- William Lane
- William Lapthorn
- William Lathan, Jr.
- William Lautman
- William Lee
- William Lehun
