The Agamemnon-class (sometimes known as the James Watt-class) steam battleships, or steam ships of the line, were a class of five 91-gun steam second rates of the Royal Navy.

The original design was produced by John Edye in 1847, as a response to the French Le Napoléon, which was rumoured to be under development.

The first ship of the class, Agamemnon, was originally designed as a two decker, 80 gun sailing ship of the line.

But was re-ordered as the first purpose built steam screw ship for the British Navy.

This article about a ship of the line of the United Kingdom is a stub.