Skagra

Doctor Skagra was a geneticist, astro-engineer, cyberneticist, neurostructuralist, and moral theologian from the planet Dronid.

Boigaphy
At some point, he departed Dronid and set up Think Tank, a space station dedicated to the goal of creating a sphere capable of draining minds and adding the contents to its database.

Following the creation of the Sphere, he set out to search for Shada and the renegade Time Lord Salyavin. (Skagra had most likely found out about Salyavin from one of the Time Lords on Dronid.) Skagra wanted to 'possess' the universe, and for this he needed Salyavin's ability to place his own mind in the minds of others. Skagra intended to do the same on a cosmic scale and in so doing impose a perfect order.

In 1979, Skagra travelled to Earth to find Salyavin. While there he obtained a copy of the mind of Professor Chronotis, in actuality Salyavin living incognito. Skagra also took the book known as The Worshipful and Ancient Law of Gallifrey, the key to Shada.

Skagra was left trapped within his Ship following the Fourth Doctor's alterations to it. (DW: Shada, WC: Shada, BFA: Shada)