Tenchi Muyo! Ryo-Ohki (天地無用! 魎皇鬼 Tenchi Muyō! Ryōōki?) is a collection of OVAs produced by AIC, initially released in Japan in 1992, and beginning the Tenchi Muyo! franchise, composed of several manga, OVAs, TV series, and other related media. The first two OVA series were later licensed and distributed in North America by Pioneer Entertainment, with Funimation taking over the rights for the third (and latest) series, and later took over the rights for the first two OVAs.

The distribution of the first OVA series was originally started in September 1992 and released six episodes that lasted until 1993. The first series was so successful that a seventh special episode was released in January 1994, followed by a second OVA series with six additional episodes that begun distribution in September 1994 and lasted for one year until September 1995. However, the second OVA series ended on a cliffhanger and it was not until nearly eight years later in 2003 that a third OVA series was distributed in Japan. The third OVA series continued the Tenchi Muyo OVA storyline with six episodes, followed by a special episode released in September 2005 that concluded the third OVA storyline.

The Ultimate Collection box set release of the first two OVAs from Geneon was one of the few releases from the company to feature THX-certified audio and video.

On October 16, 2015, a fourth OVA series was announced to be in production, with the first episode aimed for a release on November 30, 2016. The following episodes are planned to be released with an interval of 3 months each, and the final part of the series arrives on August 30, 2017.