The Isle of Bute is an island in the Firth of Clyde in Scotland, United Kingdom. It is divided into highland and lowland areas by the Highland Boundary Fault.

Formerly a constituent island of the larger County of Bute, it is now part of the council area of Argyll and Bute. Bute's resident population was 6,498 in 2011, a decline of just over 10% from the figure of 7,228 recorded in 2001[8] against a background of Scottish island populations as a whole growing by 4% to 103,702 for the same period.

The name "Bute" is of uncertain origin. Watson and Mac an Tàilleir support a derivation from Old Irish bót ("fire"), perhaps in reference to signal fires. This reference to beacon fires may date from the Viking period, when the island was probably known to the Norse as Bót. Other possible derivations include Brittonic budh ("corn"), "victory", St Brendan, or both, his monastic cell. There is no likely derivation from Ptolemy's Ebudae.

The island was also known during the Viking era as Rothesay, possibly referring to the personal name Roth or Roderick and the Old Norse suffix ey ("island"). This name was eventually taken by the main town on the island, whose Gaelic name is Baile Bhòid ("town of Bute").