Atlus Co., Ltd. is a Japanese video game developer, publisher, arcade manufacturer and distribution company based in Tokyo. A subsidiary of Sega, the company is known for the Megami Tensei, Persona, Etrian Odyssey, and Trauma Center series. Its corporate mascot is Jack Frost, a snowman-like character from their Shin Megami Tensei series. The company is also known for their Print Club arcade machines, which are selfie photo sticker booths in East Asia.

Atlus was established in April 1986 and spent its early years as a video game developer for other companies. It became a video game publisher of its own in 1989 and existed until it was merged into Index Corporation in October 2010. The Atlus name continued as a brand used by Index Corporation for video game publishing until it filed for bankruptcy in June 2013. This company was then acquired by Sega via its new subsidiary Sega Dream Corporation which renamed itself Index Corporation in November 2013. In April 2014, the non-video game assets and the Index name were spun off as a separate subsidiary of Sega, leaving the company with its video game division to be officially renamed Atlus.

A North American branch of the company, originally Atlus USA and now Atlus West, was founded in 1991 in order to focus on publishing and localizing games for North America. A European branch, handled via the London-based Sega Europe, was founded in 2017.