Pieter Geelen (born 1964) is a Dutch entrepreneur.
In 1991, he broke off his Ph.D. research in Computer Science at the Universiteit van Amsterdam to found a company called Palmtop Software with his former university mate Peter-Frans Pauwels. This company was later renamed to TomTom.
With the €100,000,000 he acquired from TomTom’s IPO in 2005, he established the Turing Foundation, a charitable organization.
In 2013 he founded the Mapcode Foundation, another charitable organization which offers the Mapcode system he invented in 2001 with Harold Goddijn.