No, not a wizard, just the same supernatural being, a Maiar, as Gandalf, Saruman were. And also, in the first age, Melian, mother of Luthien.
The Maiar are like the Vala, but less powerful. I think they are known together as the Ainur, The Holy Ones, the first creations of Iluvatar (God).
The first Dark Lord, Morgoth, was a Vala, and Sauron, Morgoth's right-hand man if you like, was a Maiar; slightly less powerful but no less dangerous.
At the begining of the third age, the Vala sent down to middle-earth some of the Maiar to guide the free peoples. The appeared in human form. (Remember, the Maiar can take on any form; Sauron appeared as a glorious Prince-like figure to decieve the Numenoreons, and Melian took on the form of an Elf so as to marry Thingol of Doriath.) They were called the Istari:Wizards. Gandalf, Saruman, and five (I think) others. Saruman, like Sauron, betrayed the Vala.
I hope that's all clear. I think I've got it all correct.

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I can see for myself that the sun is sinking
how I wish you were here to see
tell me now, I am wrong in thinking
that you have forgotten me?