Saruman was a powerful wizard that became corrupted and allied himself with Sauron. He was killed in the Shire by Grima Wormtongue and was destroyed utterly as he was denied resurrection since he had betrayed his wizardly order, the Istari.
Mauhúr was an Uruk-hai captain under the command of Uglúk, who's company was one night surrounded by a group of Rohirrim, led by Éomer. When the Uruk-hai attacked, the Rohirrim rode to meet them in a bloody battle where many orcs were slaughtered.
The orcs' captives, Merry and Pippin, found themselves outside the circle and were able to escape into Fangorn Forest. Mauhúr perished with the other orcs in the ensuing battle.