Klarbug was an Orc Captain from Gundabad.
He fought in the Battle of Five Armies and was Bolg's Lieutenant. After the Goblin Army be defeated by the Dwarves, Men and Elves, Klarbug was able to escape to Dol Guldur where he survived.
In the War of the Ring he served as Warlord of the Guldur Orcs and was one of the most trusted generals of Khamûl. He fought in a battle against the elves of Lorien in the Forest of Lothlorien and crushed a lot of elves but was punished by a spell cast by Galadriel.
He survived the magical attack of Galadriel and escaped to Dol Guldur.
He was finally killed by Celeborn ,who impaled his belly and beheaded him at the Fall of Dol Guldur.