Sandra Elaine "Sandy" Allen (June 18, 1955 – August 13, 2008) was a U.S. woman recognized as the tallest woman during her life according to Guinness World Records. She was 7'7" (231 cm) in height.

Allen wrote a book titled Cast A Giant Shadow, and appeared in the Guinness Book of World Records since 1976. Although over the years other women have taken over the title, Allen had held it for the last sixteen years of her life. Her abnormal height was due to a tumor in her pituitary gland that caused it to release growth hormone uncontrollably. At the age of twenty-two years, she underwent surgery for the condition. Lacking this procedure, Allen would have continued to grow and suffer further medical problems associated with gigantism.

She appeared in the Academy Award-winning Italian film Il Casanova di Federico Fellini, in a TV movie called Side Show, and in a Canadian/American documentary film called Being Different. The New Zealand band Split Enz wrote a song about her, "Hello Sandy Allen," released on their 1982 album Time and Tide. Allen never married and was reported to have never had a serious boyfriend.

In later years Allen used a wheel-chair because her legs and back could not support her tall stature in a standing position. At one point in her life, she was bedridden due to disease, causing atrophy of the muscles. Because of this limitation, she spent her last years in Shelbyville, Indiana, in the same retirement center as Edna Parker, the record holder of oldest living human at the time, who actually survived Allen for a few months.

The Indianapolis Star reported that Allen's friend and caretaker, Linda Fox, as saying that Allen had been suffering from kidney and blood infections; Allen died on August 13, 2008. A scholarship has since been dedicated in her name at Shelbyville High School.