AC, A.C. or Ac may refer to:
The Achaemenid Empire (; c. 550–330 BC), also called the First Persian Empire, was an empire based in Western Asia founded by Cyrus the Great.
The Academy Award for Best Picture is one of the Academy Awards presented annually since the awards debuted in 1929, by the Academy of Motion Picture Arts and Sciences (AMPAS).
An actor (also actress for women; see terminology) is a person who portrays a character in a performance.
An acronym is a word or name formed as an abbreviation from the initial components in a phrase or a word, usually individual letters (as in NATO or laser) and sometimes syllables (as in Benelux).
Academi is an American private military company founded in 1997 by former Navy SEAL officer Erik Prince as Blackwater, renamed as Xe Services in 2009 and now known as Academi since 2011 after the company was acquired by a group of private investors.
Acupuncture is a form of alternative medicine in which thin needles are inserted into the body. It is a key component of traditional Chinese medicine (TCM).
Acne, also known as acne vulgaris, is a long-term skin disease that occurs when hair follicles are clogged with dead skin cells and oil from the skin.