Louse Wies Sija Anne Lilly Berthe (Lousewies) van der Laan (Rotterdam, February 18, 1966) is a former Dutch politician and the leader of the parliamentary group of the social liberal Democrats 66 (D66) in the Lower House for six months in 2006. She was a Member of the European Parliament between 1999 and 2003 in the ELDR group.

Life before politics
In 1999 she became head of the D66 list for the European Elections. She became chairwoman of the parliamentary party and member of the parliamentary party board of the ELDR. In the European Parliament she was active on a range of issue focusing on civil liberties, environmental affairs, budget and foreign affairs. In the European Parliament she was vice-chairwoman of the Committee on Budget Control between 1999 and 2002, vice-chairwoman of the Committee on Liberties and Civil Rights, Justice and Home Affairs between 2002 and 2003. She was member of the Committee on the Rights of the Woman and Equal Chances between 1999 and 2003, the delegation for relations with the Palestinian Authority between 1999 and 2002. Between 1999 and 2002 she was a substitute for the Committee on Environmental Protection, Public Health and Consumers' Policy and a substitute for the delegation for relations with Slovakia. Between 2002 and 2003 she was a substitute for the Budget Committee. She founded the Intergroup on Food Safety, the Campaign for Parliamentary Reform.