Indomptable, Sans Pareil, Indivisible, Foudroyant, Formidable, Guillaume Tell, The Tonnant class was a series of eight 80-gun ships of the line designed in 1787 by Jacques-Noël Sané, whose plans for the prototype were approved on 29 September 1787.

With sixteen gunports on the lower deck on each side (although only fifteen of these ports on each side were routinely provided with 36-livre guns) these were the most effective two-deckers of their era.

All but one of the eight ships were to be captured or destroyed by the British Navy, and four of these were to enjoy long careers in their new service.

The prizes were highly regarded by British sea officers, but they proved costly and time-consuming to maintain.

The design dimensions of these ships (in French pieds of 324.84mm) were 182.5 overall length, 167 keel length x 47.0 breadth x 23.5 depth in hold (see General Characteristics box for metric equivalents and those in UK/US units).