Abū-Sa'īd Abul-Khayr, Persian Sufi poet (d. 1049)
Abusa'id Abolkhayr or Abū Saʿīd Abū'l-Khayr (December 7, 967 - January 12, 1049), also known as Sheikh Abusaeid or Abu Sa'eed, was a famous Persian Sufi and poet who contributed extensively to the evolution of Sufi tradition.

The majority of what is known from his life comes from the book Asrar al-Tawhid (اسرارالتوحید, or "The Mysteries of Unification") written by Mohammad Ibn Monavvar, one of his grandsons, 130 years after his death.

The book, which is an important early Sufi writing in Persian, presents a record of his life in the form of anecdotes from a variety of sources and contains a collection of his words.

During his life his fame spread throughout the Islamic world, even to Spain. He was the first Sufi writer to widely use ordinary love poems as way to express and illuminate mysticism, and as such he played a major role in foundation of Persian Sufi poetry. He spent most of his life in Nishapur.