Saruman, like Gandalf, is one of the five Maiar (gods) who were sent to Middle-earth to guide its inhabitants. Saruman was known as Curumo and was the greatest and wisest of the five hence his name "Saruman the Wise" and not "Saruman the Original."
But Saruman is corrupted. In Orthanc, the tower of Isengard, Saruman has been consulting a Palantír . Through it, Sauron has corrupted him. And although Saruman seeks power for himself (and plans to turn on Sauron), he has betrayed the elves and men and all free people to gain it.