Richard Daystrom (mirror)

In the mirror universe, Doctor Richard Daystrom was a Terran scientist in the service of the Terran Empire during the 23rd century. He was considered one of the most brilliant and influential scientific geniuses in Terran history. 
In the 2260s, Daystrom created a multitronic unit known as the M-5 computer which utilised much more advanced computer technology than the duotronic computer commonly in use at that time. Designed as a wargame simulator for the Imperial Starfleet, it was put in command of the ISS Excalibur in 2268. In this wargame, it faced off against the ISS Enterprise, ISS Lexington, ISS Potemkin and ISS Hood. However, when it was supposed to use low-powered phasers, it instead fired on the other ships at full power, destroying the Potemkin and nearly destroying the Enterprise. Using an unorthodox strategy, the Enterprise's captain Spock and his first officer, Montgomery Scott, brought up the datacharts of the command consoles of the other two fully-crewed ships, knowing that M-5 would have changed the prefix codes of Excalibur to prevent what he was about to attempt. He armed the self-destruct package of both the Lexington and the Hood and detonated them when they were in close proximity to the Excalibur, vaporizing all three ships. 
The incident was reported to Starfleet Command as an accident but Spock correctly believed that it was an attempt to assassinate him by his enemies in Starfleet. Dr. Daystrom had assured Commodore Robert Wesley, captain of the Lexington, that his creation could indeed destroy the Enterprise, but had not brought up the possibility that it would turn on them as well. Wesley would pay for that mistake with his life.
His accomplishments were well-known, even almost 80 years after the fall of the Terran Empire. In 2371, the archaeologist for hire Vash described Noonien Soong as a genius, comparing him to Daystrom and Zefram Cochrane.