A haystack is a stack of hay.

Haystack or Haystacks may also refer to:

• Haystacks (Monet series), a series of Impressionist paintings by Claude Monet

• Haystak (born 1973), American rapper
• Haystacks Calhoun (William Calhoun; 1934–1989), American professional wrestler
• Giant Haystacks (Martin Ruane; 1946–1998), British professional wrestler

• Haystack, Queensland
• Haystack Island, an island in South Australia

• Haystack, Newfoundland and Labrador

• Haystacks (Lake District), a mountain in England

• Haystack, New Mexico, a census-designated place
• Haystack Observatory, a group of radio-telescope astronomical observatories in Massachusetts
• Haystack Rock, a formation just off the coast at Cannon Beach, Oregon
• The Haystacks, enigmatic sandstone mounds in Loyalsock Creek, Sullivan County, Pennsylvania

• Haystack (MIT project), a personal information management/semantic web research software project
• Haystack (software), a network traffic obfuscator and encryptor

• Haystack (food)
• Haystacks: Autumn, a c. 1874 painting by Jean-François Millet
• Haystack Prayer Meeting
• Mogote, a haystack-shaped, erosional, geomorphic structure

• Haystack Mountain (disambiguation)
• All pages with titles containing Haystack