Jack Sim Juek Wah, also known as Mr Toilet, is a Singaporean entrepreneur and philanthropist who is the founder of the World Toilet Organization and World Toilet Day initiative. He is also the founder of the Restroom Association of Singapore.

The World Toilet Organization (WTO) is a global non-profit organization whose goal is to improve toilet and sanitation conditions worldwide. It was founded in 2001 with 15 members and has now grown to 151 member organizations in 53 countries. The WTO is also the organizer of the World Toilet Summit, the Urgent Run and initiated the United Nations World Toilet Day.