Dr. Proton

Dr. Proton is the main antagonist of the original Duke Nukem game.

After a terrible radiation accident that altered his brain, Dr. Proton took to the underworld and developed an army of advanced robots -- called Techbots. In 1997 Doctor Proton and his army of Techbots took control of Earth's largest city. He communicates with Duke by way of TVs found periodically on different levels. Half his face is covered by a metal plate and he moves around on a flying chair that shoots.

Proton had a secret hideout hidden deep underground on earth in the first episode. Proton has a base on the Moon (perhaps the Tiberius Station) which he escapes to when the first episode ends. When Duke catches him there, he escapes to the future with a time machine in the end of the second episode, but Duke follows him and destroys him there in the third and final episode.