Each of the Maiar was associated with one or more particular Vala, and were of similar stock, though less powerful. For example, Ossë and Uinen, as spirits of the sea, belonged to Ulmo, while Curumo, who came to be known in Middle-earth as Saruman, belonged to Aulë the Smith.
Others included Sauron (originally also of Aulë's people), Aiwendil, who was known in Middle-Earth as Radagast the Brown and belonged to Yavanna, and Olórin, known as Gandalf, who belonged to Manwë and Varda, but his ways took him often to the house of Nienna, and of her he learned pity and patience, which perhaps aided him in his later struggles to unite the Free peoples of Middle-Earth against the power of Sauron.
Alatar and Pallando, known as the Blue Wizards, travelled to the east, and never returned to the west. Their fate is unknown. The Balrogs, like Sauron, were Maiar corrupted by Melkor. Their associated Vala is not known. Melian served both Vana and Estë.