John Patrick Crichton-Stuart, 3rd Marquess of Bute (1847-1900) is remembered chiefly for his links with the city of Cardiff, Wales, and particularly for the restoration of Cardiff Castle.

The 3rd Marquess was born at the family seat of Mount Stuart in Scotland. He inherited his father's title, as well as his fabulous wealth, as a baby. Educated at Harrow School and Oxford, Bute was converted to Roman Catholicism in 1868. Unlike his industrialist father, the 3rd Marquess was cultured and a scholar. Having had Mount Stuart remodelled, he began on his Welsh possessions in the mid-1860s, employing the architect and designer William Burges to convert Cardiff Castle in mock-medieval style. Its fantastic interior decoration can still be seen. In 1871, Burges began work on the smaller Castell Coch, which was decorated in similar style and is often used as a film set because of its outward appearance.

Bute is supposed to have inspired Benjamin Disraeli's novel, Lothair.