Ache (c. 1500s - 1572; Old Spanish orthography: Rája Aché or Raxa Ache, also known as Rája Matandâ ("the Old King"), was King of Luzon who ruled from the kingdom's capital Maynila now the capital of the Republic of the Philippines.

While still the Crown Prince of Luzon and the grand admiral for the King of Brunei, Ache married a princess of Brunei in 1521. He was the King of Luzon in 1570 when his nephew, the heir apparent (raja muda) Sulayman together with Bunao, Lakandula, the lord of Tondo, engaged in a battle with the Martin de Goiti naval detachment to Luzon augmented by Cebuano military volunteers and part of the Legaspi expedition of Spain commissioned from New Spain to find the Maluku Islands. This battle resulted in the fall of Manila and the capture of 13 pieces of artillery.

Among the Spanish accounts of Ache's capture, that of Rodrigo de Aganduru Moriz is considered among those which extensively record Ache's statements. Details of Ache's early life are thus usually based on the Aganduru Moriz account.

According to this document, Ache's unnamed father died when he was still very young, and his mother acceded as ruler of Maynila. In the meantime, Ache was raised alongside his cousin, the ruler of Tondo, and this person is identified by some to be Bunao Lakandula.

During this time, the "young prince" Ache realized that his mother was being "slyly" taken advantage of by his cousin, the ruler of Tondo, who was encroaching on territory belonging to Maynila. When Ache asked his mother for permission to address this matter, she refused and told him to keep his peace.

Ache could not accept this, and thus left Maynila with some of his late father's trusted men to see his "grandfather", the Sultan of Brunei, and request assistance. The Sultan responded by giving Ache a position as commander of his naval forces. Pigafetta noted that Ache was "much feared in these parts", but especially by the non-Muslims, who considered the Sultan an enemy potentate. He was a strict enforcer of Islamic rule in Brunei and the Philippines as he waged war against Tondo. The Sultan commended him for successfully sacking the Buddhist city of Loue in southwest Borneo, which adhered to the old religion and resisted the authority of the Sultanate.

Aganduru Moriz recounts that in 1521, Ache was in command of the Bruneian fleet when they chanced upon what remained of the Magellan expedition, under the command of Sebastian Elcano, somewhere off the southeastern tip of Borneo. Rizal notes that Ache had just won a naval victory at the time, and Rizal and Dery both say Ache was on his way to marry a cousin – a ritual which Scott describes as the usual way that nobles at that time gained influence and power. (Luciano PR Santiago notes that this practice helps explain the close interrelationships among the ruling houses in Manila, Brunei and Sulu.)

Dery notes that Ache's decision to attack must have been influenced by a desire to bring Elcano's ship back to Manila bay, for use as leverage against his cousin, the ruler of Tondo.