The Spanish–Chamorro Wars, also known as the Chamorro Wars and the Spanish–Chamorro War, refer to the late seventeenth century unrest among the Chamorros of the Mariana Islands in the western Pacific Ocean against the colonial effort of Habsburg Spain. Anger at proselytizing by the first permanent mission to Guam, which was led by Diego Luis de San Vitores, and a series of cultural misunderstandings led to increasing unrest on Guam and a Chamorro siege of the Hagåtña presidio incited by maga'låhi (Chief) Hurao in 1670. Maga'låhi Matå'pang killed San Vitores in 1672, resulting in a campaign of Spanish reprisal burnings of villages through 1676. Local anger at the attacks against villages resulted in another open rebellion led by Agualin and a second siege of Hagåtña. Governor Juan Antonio de Salas conducted a counter-insurgency campaign that successfully created a system of collaboration in which Guamanians turned in rebels and murderers and transferred most of the people from about 180 villages to seven towns, a policy known as reducción. By the early 1680s, Guam was largely "reduced," or pacified.

The Chamorro people are the Indigenous people of the Mariana Islands, politically divided between the United States territory of Guam and the encompassing Commonwealth of the Northern Mariana Islands in Micronesia, a commonwealth of the US. Today, significant Chamorro populations also exist in several U.S. states, including Hawaii, California, Washington, Texas, Tennessee, Oregon, and Nevada, all of which together are designated as Pacific Islander Americans according to the U.S. Census. According to the 2000 Census, about 64,590 people of Chamorro ancestry live in Guam and another 19,000 live in the Northern Marianas.