The term "Maia" is singular, while "Maiar" refers to the plural group. The same goes for Vala and Valar. Gandalf, Saruman, and the other wizards of J.R.R. Tolkien's world are part of a species ...

In The Lord of the Rings, before Sauron was an extremely feared and powerful enemy of Middle Earth, he was an immensely gifted Maia. The Maiar are spirits that helped the Valar to build and shape ...