Lars Anthonius Johannes Boom (born 30 December 1985) is a professional cyclo-cross and mountain bike racing cyclist from the Netherlands. He has also competed professionally in road racing, having raced between 2004 and 2019.

Born in Vlijmen, Netherlands, Boom has also previously competed for Rabobank and their junior and continental teams over two spells with the team, as well as Astana. Boom won the cyclo-cross world championships in 2008. He has also been the Dutch national cyclo-cross champion in his discipline from 2001 to 2012 – junior cyclo-cross champion from 2002 to 2003, under-23 champion from 2004 to 2006, and the elite champion from 2007 to 2012.