Also called: Men-orcs, Orc-men.{1}
A special kin of Orcs, developed through crossbreeding between Orcs and very corrupted Men. The Half-orcs were of human stature, but looked more like Orcs. They were produced by Sauron and Saruman in the Third Age, and used as soldiers.
Known activities: The only event that the Half-orcs were definitely involved in was the takeover of the Shire by Saruman in 3019 TA: all the Chief's men were Half-orcs {2}. They were probably also involved in the battle between the troops of Isengard and the Rohirrim on February 25, 3019 TA, where Theodred son of Theoden fell {3}.
See also: Orcs
Sources:
1. HME vol. 10 Myths Transformed X
2. LOTR vol. 3 The Scouring of the Shire
3. UT The Battles of the Fords of Isen
Hypertextual System by FMI Publishing, 1995