Nuestra Señora de la Santísima Trinidad, nicknamed La Real, sometimes confused with the merchant galleon Santísima Trinidad y Nuestra Señora del Buen Fin) was a Spanish first-rate ship of the line and was the largest warship in the world when launched. She originally had 112 guns; this was increased in 1795–96 to 130 guns by closing in the spar deck between the quarterdeck and forecastle, and to 136 guns around 1802, thus creating what was in effect a continuous fourth gundeck although the extra guns added were actually relatively small. She was the heaviest-armed ship in the world when rebuilt, and bore the most guns of any ship of the line outfitted in the Age of Sail.

In the rating system of the Royal Navy used to categorise sailing warships, a first rate was the designation for the largest ships of the line. Originating in the Jacobean era with the designation of Ships Royal capable of carrying at least 400 men, the size and establishment of first-rates evolved over the following 250 years to eventually denote ships of the line carrying at least 80 guns across three gundecks. By the end of the eighteenth century, a first-rate carried no fewer than 100 guns and more than 850 crew, and had a measurement (burthen) tonnage of some 2,000 tons.