El Gordo de la Primitiva (literally the fat one of the primitive lottery, sometimes translated as the big one), commonly known simply as El Gordo, is one of the lotteries operated by Loterías y Apuestas del Estado, the Spanish government lottery authority.

The term 'El Gordo' is also used to refer to the largest prize awarded in the Spanish Christmas Lottery and to a lesser extent in other Spanish lotteries.

Tickets consist of two grids: one with numbers from 1 to 54 and a second with numbers from 0 to 9. Players must pick five numbers from the first grid and one from the second (the key number). The key number also determines whether the ticket receives a refund.

Tickets can be bought from Monday to Saturday in over eleven thousand locations in Spain and cost €1.50 per grid.

By selecting six to eleven numbers in the first grid, players can make multiple bets (from 6 to 462) with the same ticket.

Draws are held every Sunday at 13:00 (GMT+1).

Five numbers are drawn at random from 1–54, followed by one number for the key number from 0–9. Prizes are awarded to tickets whose numbers match the drawn ones. First prize is for a perfect match (5+1), second for 5+0, third for 4+1, and so on down to 2+0, totaling eight prize categories. Tickets whose key number matches the drawn key number only are entitled to a refund of the amount played.

A ticket can hold more than one bet, but each bet cannot win more than one prize.