William Mapother, Actor: Lost. William Mapother was born on April 17, 1965 in Louisville, Kentucky, USA as William Reibert Mapother Jr. He graduated from the University of Notre Dame with a B.A. in English. He is the co-founder of the film finance marketplace Slated. He is known for his work on Lost (2004), In the Bedroom (2001) and Another Earth (2011).