This is Kagato, one of the coolest villains in Tenchi Muyo.  Extraordinarily powerful and merciless, he nearly killed Tenchi before he even got near him.

He had enslaved Ryoko for thousands of years, forcing her to do his bidding.  He captured his teacher (Washu) and had imprisoned her for about 5,000 years.

His powers include being able to utilize Ryoko's gems to give him quite a power boost.  The ship (Soja) can also use the power within the gems.  He has a lightsword which is green and quite long.  A master swordsman, he mopped the floor with Tenchi and had quite a bit of fun with Yosho as well.  Yosho was only able to hold him back using a lighthawk wing.

Having a thing for organ music, he plays a cool song while Ryoko and Aeka made their way to his primary room.

Kagato was killed by Tenchi after Tenchi transformed and began using the lighthawk wings.

His ship is extremely powerful.  Basically a miniature death star, it has more than enough power to vaporize a planet.  And according to what Kagato was doing, it even has enough power to overcome the THREE lighthawk wings generated by Ryu-Oh.

No where near as evil or skilled as his OVA counterpart, he's the primary villain of Tenchi Universe.

He managed to steal the throne of Jurai during Aeka's absence, masquerading as Yosho.  Also having the ability to utilize the Jurai power to extremes, he was able to keep his youthful form, increase his power far beyond that of Yosho, and basically trash everybody that challenged him.

However, the way he was killed was too quick.  Tenchi's sword started glowing after we see a bunch of cool scenes... and the fight only lasted a few moments.

We really didn't get to see enough of him.  Most of the time it was just an evil grin. :)