Ratu was an Indonesian music duo formed in 1999 with Maia Estianty, then the wife of musician Ahmad Dhani, on instruments and Pinkan Mambo on vocals. Ratu entered the Indonesian musical scene with their first album, Bersama. After a short break caused by Mambo's departure in 2004, the group formed anew with Mulan Kwok as vocalist. This new line-up proved more successful, with their most successful songs – "Teman Tapi Mesra" and "Lelaki Buaya Darat" ("Womaniser") – released in this period; both song titles later became common terms in the Indonesian vocabulary. The group's second studio album, No. Satu, sold 200,000 copies on the day of its release, a record for an album by an Indonesian female group. The group dissolved in 2007.

Maia Estianty, formerly known as Maia Ahmad during her marriage to fellow musician Ahmad Dhani, is an Indonesian singer and composer.