- Association of Corporate Counsel
- American Chemistry Council
- Air Coordinating Committee
- (New Zealand) Accident Compensation Corporation
- (New Zealand, by extension) The government accident compensation scheme in New Zealand, administered by the Accident Compensation Corporation.
- (Internet, slang) author-created character, referring to the practice of creating a new character wholesale who is added into a fanfic's cast of 'official' characters. (The characters created by the official original creator are not considered ACC.) The practice is generally discouraged unless the character plays a small role and never overtakes the existing characters' importance in a story; those that do are often accused of being "Mary Sues" or "Self Inserts".