An unnamed rider
Shruikan is the name of his dragon :)
His name is Shruikan and he's Galbatorix's partner.
Shruikan, against his will, is the name of Galbatorix's current dragon.
His first dragon was killed by Urgals. Shruikan, his second dragon he forced to serve him, is still with him.
Galbatorix's first dragon was Jarnunvosk.He was killed by urgals.
Shruikan was killed when Arya used the ancient Rider's sword to stab him through the eye into his brain during the final battle of the Inheritance Cycle. This act of bravery and skill allowed Eragon to finally defeat Galbatorix and end Shruikan's reign of terror.
The Varden-Surda-Elves-Dwarves-Urgals-Eragon and Saphira-Angela-Werecats- Vs. The Empire-Galbatorix and Shruikan-Murtaugh and Thorn-Eldunari-The soldiers of Uru'baen
appearing dragonriders are: Eragon - Saphira Brom (dragon died before book 1) - Saphira Murtagh - Thorn Oromis - Glaedr Galbatorix - Shruikan there are also some others mentioned, like the Eragon, that Eragon was named after, but these are the ones that actually appear. you´re welcome :)
He is black.
Brom, Oromis, Ajihad, Galbatorix, The Twins, Carn, Sand, Shruikan, The Forsworn, The Ra'zac, Lord Barst, Durza, Varaug, Garrow, Selena, Glaedr (body death), Queen Islanzadi, Wyrden, Hrothgar. Those are all the main characters I can think of, may have missed a few though.
There are only 4 dragons people know about in the first three books. There is Saphira, Eragons dragon, Glaedr, Oromis' dragon, Shruikan, Galbatorix's dragon,and Thorn, Murtagh's dragon. There will be another dragon in the 4th book, which isn't out yet, and Christopher Paolini said himself that it was going to be green.
Galbatorix