Atasi Corporation was an American 5+1⁄4-inch hard disk drive manufacturer company founded in California in 1981.

Atasi began selling products the following year in 1982 and was one of the first 5+1⁄4-inch hard disk drive manufacturers to develop and utilize closed-loop technologies such as voice-coil actuators.

Despite being considered a pioneer within its industry and having widespread adoption of its products in the high-end microcomputer market, the company had financial problems throughout its lifetime. Atasi went through failed agreements, bankruptcy, and was acquired by Tandon then Western Digital in 1987.

The company briefly reemerged with the name of Atasi Technology in 1990. Atasi Technology sold Apple compatible external hard disk drives and rebranded Priam drives until 1992.

Atasi was incorporated in 1981. It was principally founded by Frank C. Gibeau, while Paul L. Farmer, Stanley F. Brown, and Garold W. Plonczak were three of four other founding partners. The name "Atasi" was a Native American word for a type of club used in warfare; Gibeau, a history enthusiast, chose the name for its Native American origins.

Prior to founding Atasi, Gibeau was manager of Verbatim's hard disk drive division. He also had over 17 years of experience at companies such as IBM and Memorex.

Most other hard disk drive companies at the time were using open-loop technologies such as stepper motors for controlling head movement. Stepper motors were slow and not capable of keeping up with the ever increasing capacity and density of the platters on hard disk drives. Additionally they were more prone to errors and had issues such as overheating when used for prolong periods of time. Hard drives utilizing stepper motors and band actuators like the Seagate ST-506/ST-412, had an access time of 85 ms average with up to 205ms and a 255-345 tracks per inch density.

Gibeau along with Farmer, Brown, and Plonczak developed their own closed-loop technologies to be used in their products.