A full breakfast or fry-up is a substantial cooked breakfast meal often served in Britain and Ireland. Depending on the region, it may also be referred to as a full English, a full Irish, full Scottish, full Welsh or Ulster fry.

The typical ingredients are bacon, sausages, eggs, black pudding, tomatoes, mushrooms, and fried bread or toast and the meal is often served with tea. Baked beans, hash browns, and coffee (in place of tea) are common contemporary but non-traditional inclusions.

The fried breakfast became popular in Great Britain and Ireland during the Victorian era; while the term "full breakfast" does not appear, a breakfast of "fried ham and eggs" is in Isabella Beeton's Book of Household Management (1861).

Many of the ingredients of a full breakfast have long histories, but "large cooked breakfasts do not figure in English life and letters until the 19th century, when they appeared with dramatic suddenness". Across the British Isles and Ireland, early modern breakfasts were often breads served with jams or marmalades, or else forms of oatmeal, porridge or pottage. Eggs and bacon started to appear in breakfasts in the seventeenth century, but they were not the only meats consumed in breakfasts at that time. The rising popularity of breakfast was closely tied to the rise of tea as a popular morning drink. Of note were the lavish breakfasts of the aristocracy, which would centre on local meats and fish from their country estates.

The fried breakfast became popular in Great Britain and Ireland during the Victorian era. Cookbooks were important in the fixing of the ingredients of a full breakfast during this time, and the full breakfast appeared in the best-selling Isabella Beeton's Book of Household Management (1861). This new full breakfast was a pared-down version of the country breakfasts of the upper class, affordable to the emergent middle classes and able to be prepared and consumed in a shorter time before a day's work. The full breakfast reached its peak of popularity in Edwardian Britain, and despite a decline following the food shortages of World War II, new technologies of food storage and preparation allowed it to become a staple of the working class in the 1950s. Since then the full breakfast has declined in popularity as a daily meal, due to perceived concerns about health and its lengthy preparation compared to convenience-food breakfasts. However, the meal remains popular as an occasional, celebratory or traditional breakfast.

It is so popular in Great Britain and Ireland that many cafés and pubs offer the meal at any time of day as an "all-day breakfast". It is also popular in many Commonwealth nations. The full breakfast is among the most internationally recognised British dishes along with bangers and mash, toad in the hole, shepherd's pie, fish and chips, roast beef, Sunday roast, cream tea and the Christmas dinner.

There is no fixed menu or set of ingredients for a full breakfast. A common traditional English breakfast typically includes back bacon, sausages (usually pork), eggs (fried, poached or scrambled), fried or grilled tomatoes, fried mushrooms, black pudding, baked beans, and toast or fried bread. Bubble and squeak is a traditional accompaniment but is now more commonly replaced by hash browns.

A poll by YouGov in 2017 found the following to be on more than 50% of 'ideal' Full English breakfasts: bacon; sausage; beans; bread (either toast or fried); eggs (fried, scrambled or poached); hash browns; mushrooms (fried or grilled); and tomatoes (fried, grilled or tinned). Black pudding was the least popular of the traditional ingredients, chosen 35% of the time, and 26% of people included either chips or sautéed potatoes.