The Observer is a British newspaper, published on Sundays. In the same place on the political spectrum as its daily sister papers The Guardian and The Guardian Weekly, whose parent company Guardian Media Group Limited acquired it in 1993, it takes a social liberal or social democratic line on most issues. First published in 1791, it is the world's oldest Sunday newspaper

The first issue, published on 4 December 1791 by W.S. Bourne, was the world's first Sunday newspaper. Believing that the paper would be a means of wealth, Bourne instead soon found himself facing debts of nearly £1,600. Though early editions purported editorial independence, Bourne attempted to cut his losses and sell the title to the government. When this failed, Bourne's brother (a wealthy businessman) made an offer to the government, which also refused to buy the paper but agreed to subsidise it in return for influence over its editorial content. As a result, the paper soon took a strong line against radicals such as Thomas Paine, Francis Burdett and Joseph Priestley.

The paper was banned in Egypt in February 2008 after reprinting cartoons allegedly insulting the prophet Mohammed.