David Lennox Mills (June 3, 1938 – January 17, 2024) was an American computer engineer and professor emeritus at the University of Delaware.

[5] While at Michigan, he worked on the ARPA-sponsored Conversational Use of Computers (CONCOMP) project and developed DEC PDP-8-based hardware and software to allow terminals to be connected over phone lines to an IBM 360 mainframe.

[6][7] In 1977, Mills began working at COMSAT on synchronizing the clocks of computers connected to ARPANET, inventing the Network Time Protocol (NTP).

[5][8][9] NTP is intended to synchronize all participating computers to within a few milliseconds of Coordinated Universal Time (UTC).

[16] In 2008, Mills was elected a member of the National Academy of Engineering (NAE) for contributions to Internet timekeeping and the development of the Network Time Protocol.