In J. R. R. Tolkien's fictional universe of Middle-earth, Hallas was the thirteenth Ruling Steward of Gondor.
Hallas was born in T.A. 2480 and succeeded his father Cirion at his death in T.A. 2567. Calenardhon had been given by his father to the Éothéod, and this people began to migrate to the land. Hallas devised the names Rochand and Rochirrim for the land and its people, which became Rohan and Rohirrim in the Sindarin dialect of Gondor. In effect Gondor had been halved in size, but it had gained a strong ally to the north.
War never ceased on Gondor's eastern borders as the Balchoth were not completely destroyed, but they were no longer a serious threat. More a problem were the Corsairs of Umbar, who kept raiding the coasts.
He was followed by his son Húrin II at his death in T.A. 2605.
In some early variants of the Quenta Silmarillion tradition published in The History of Middle-earth, Hallas is also the name of the son of Orodreth. The character of Orodreth's son slain by Orcs reappeared often and under different names, but was later abandoned and finally replaced by Gil-galad, later High King of the Noldor.