Pieter van Aelst or Pieter van Aelst III (c. 1495 – c. 1560) was a Flemish tapestry weaver whose workshop commenced by his grandfather was one of the leading weavers of Flanders in the first half of the 16th century. He should not be confused with Pieter Coecke van Aelst (1502-1550), a Flemish painter who was also a significant tapestry designer.