David Walsh (born 1961) is an Australian mathematician, art collector, and entrepreneur. He made his fortune by developing complex betting systems based on mathematical models, primarily in the field of horse racing. He is internationally known for founding the Museum of Old and New Art (MONA) in Hobart, Tasmania, which opened in 2011. Funded entirely by his personal fortune, the museum is the largest private art institution in the Southern Hemisphere and is distinguished by its provocative collections, centered on the themes of sex and death. The institution has had a significant impact on Tasmania's tourism and culture, a phenomenon known as the "MONA effect." In addition to the museum, his business ventures include the Moorilla winery and the Moo Brew brewery. He is also the author of the autobiography "A Bone of Fact." For his contribution to the arts and the community, he was appointed an Officer of the Order of Australia in 2016.