The Battle of Bloody Bay, or Blàr Bàgh na Fala in Scottish Gaelic, is a naval battle fought near Tobermory, Scotland on the coast of Mull, two miles north of Tobermory, between John of Islay, Earl of Ross, the Lord of the Isles and chief of Clan Donald; and his son, Angus Og Macdonald.

The precise date of the battle varies in sources, from 1480 to 1483.

After the battle, in which Angus Og Macdonald emerges victorious, the latter seizes power from his father, and holds it for the better part of a decade.

However, Angus's victory will prove pyrrhic.

Many clansmen died in the battle and nearly half the clan's fleet is sunk, as a result of which the power of the Lords of the Isles is henceforth greatly diminished.

Angus, last of the independent Lords of the Isles, will himself be murdered in 1490.