HP Sauce is a British brown sauce, the main ingredients of which are tomatoes and tamarind extract. It was named after London's Houses of Parliament. After making its first appearance on British dinner tables in the late 19th century, HP Sauce went on to become an icon of British culture. It was the best-selling brand of brown sauce in the UK in 2005, with 73.8% of the retail market. The sauce was originally produced in the United Kingdom, but is now made by Heinz in the Netherlands.

HP Sauce has a tomato base, blended with malt vinegar and spirit vinegar, sugars (molasses, glucose-fructose syrup, sugar), dates, cornflour, rye flour, salt, spices and tamarind. It is used as a condiment with hot and cold savoury food, and as an ingredient in soups and stews.

The picture on the front of the bottle is a selection of London landmarks including Elizabeth Tower, the Palace of Westminster, and Westminster Bridge.