Iyo 壹與 was a queen of Wa, a land now called Japan. She was a relative and the successor of Queen Himiko 卑彌呼, who ruled Wa until her death in 248.

Following Himiko's death, there were considerable succession disputes. Many males were killed during those disputes. Eventually it was Iyo who ascended the throne. When she did she was only 13 years old.

Like Himiko before her, she is said to have had substantial shamanic or spiritual abilities as well as wielding secular political power. Iyo continued, or restored, tributary relations between Wa and Wei; Wei officials were included among her advisors, and she sent an embassy of twenty individuals, led by her grand steward Isako, to accompany some of these Chinese officials back to China.