The Wizards of Middle-Earth...

[narfforc]

Of this Order the number is unknown; but of those that came to the North of Middle-earth, where there was most hope (because of the remnant of the Dunedain and of the Eldar that abode there), the chiefs were five.


THE ISTARI, UNFINISHED TALES.

This could be read to imply there were others who were not the chief five.

[Raynor]

Originally Posted by narfforc

This could be read to imply there were others who were not the chief five.

However, LotR implies that there were only five:

Originally Posted by Tale of Years, RotK

The two highest of this order (of whom it is said there were five) were called by the Eldar Curunir, "the Man of Skill", and Mithrandir, "the Grey Pilgrim", but by Men in the North Saruman and Gandalf.

There are various similar statements in the letters, such as:

Originally Posted by Letter #203

There were five wizards and that is just a unique part of history.

[The Might]

I know for a fact that the account from the Unfinished Tales is older, thus the idea that there were only 5 wizards seems to me as the more likely idea.