Uglúk, son of Ukukukuk was an uruk-hai leader during the War of the Ring.
Uglúk in rage

Uglúk, the chief of uruk-hai

 He fought at Amon Hen, but he survived. He led the uruk band, which went back to Saruman. His band, led by him, Lugdush and Hodhvarz met another uruk band, Mauhúr's, and they joined. This large uruk-hai party met again another orc group led by Grishnákh, Snargab, Uslak, and Dûrbuhûk . They all were killed by rohirrim.