Rook vs Bishop Endings
In theory, a Rook is worth 5 pawns, and the Bishop is worth only 3 pawns. That gives the Rook a two pawn advantage, which sounds like an easy win, and it usually is. In a Rook-vs-Bishop ending with equal pawns, the Rook will usually win except in special cases (e.g. the Bishop is supporting a very advanced passed pawn).
Endgames where the Bishop has an extra pawn or two are more interesting, and also more common in practice. The Rook should still win with one extra pawn (R vs B+P with extra pawns), but again with exceptions for advanced passed pawns.