For the research project, see Penny Black (research project).

The Penny Black was the world's first official adhesive postage stamp, issued by the United Kingdom on May 1, 1840, for use from May 6.

The idea of an adhesive stamp to indicate prepayment of postage was part of Rowland Hill's 1837 proposal to reform the British postal system. A companion idea which Hill disclosed on 13 February 1837 at a government inquiry was that of a separate sheet which folded to form an enclosure or envelope for carrying letters. At that time postage was charged by the sheet and distance involved and the inquiry Hill noted that the stamp idea might obviate the envelope.

In the event when Hill was given a two-year contract to run the new system he and Henry Cole ran a competition for the best way to prepay letters. None of the 2600 entries were good enough, so in the end Hill launched the service in 1840 with an envelope bearing a reproduction of a design created by the artist William Mulready and a stamp bearing an reproduction of the profile of the reigning British monarch, Queen Victoria. There are also references on the record to covers bearing the Mulready design. To this day, all British stamps bear a profile of the reigning monarch somewhere on the design, and are the only nationality of stamp that do not name their country of origin.

In 1839, the British Treasury had announced a competition to design the new stamps, but none of the submissions were considered suitable, and the Treasury chose instead to use a profile of Victoria. The head was engraved by Charles and Fredrick Heath based on a sketch provided by Henry Cole. Cole's sketch was in turn based on the head by William Wyon, that had been done for a medal used to commemorate the visit of Queen Victoria to the City of London in the year she ascended the throne, 1837. The word "POSTAGE" appeared at the top of the stamp, to denote its intended use and "ONE PENNY" at the bottom, indicating the amount that had been pre-paid for the transmission of the letter to which it was affixed. The background consisted of finely engraved engine turnings. In addition, the two upper corners contained star like designs and the lower corners contained letters designating the position of each stamp in the sheet, "A A", "A B", and so forth. As the name suggests, the stamp was printed all in black. The stamps were printed by Perkins Bacon.

Although May 6 was the official first date when the labels were available for the pre-payment of postage, there are known covers postmarked May 2, due to postmasters selling the stamps from 1 May. Stamps used on letters prior to the 6 May should have been treated as un-paid and charged double the rate on delivery. A single example is also known on cover dated 1 May 1840.

The Penny Black was in use for only a little over a year; in a manner familiar to technologists of the 20th century, usage experience showed that a red cancellation on a black stamp was rather hard to see, as well as the fact that the red cancellation could be cleaned from the stamps allowing its re-use and thus depriving the Post Office of revenue. In 1841 the Treasury switched to the Penny Red and cancelled it with black ink. The black ink which was much more effective as a cancellation was also harder to remove. The re-use of stamps by the un-cancelled portions of two stamps to form an unused whole impression continued and in 1864 the stars in the top corners were replaced by the check letters, as they appeared in the lower corners, but in reverse order.

The Penny Black was printed from 11 plates, however as plate 1 was completely overhauled due to excessive wear, it is generally considered as two separate plates, 1a and 1b. When the printings in red were made the existing plates used for some of the black stamps were used as well as new plates purely for the red printings. (See information on Penny black printing plates)

An original printing press for the Penny Black is on display to the public at the British Library in London.

The Penny Black is readily available, but because of its significance is in great demand by collectors and therefore not cheap; in 2000 a used copy cost about US$200, and an unused copy about US$3,000. (By contrast, a used Penny Red was $3.)

In addition to the general issue of the Penny Black postage stamps, a similar stamp was produced which had the letters V and R in the top corners replacing the stars. The intention of this issue was for use on official mail. Following the acceptance by the general public of the postage stamps and the ridicule of the Mulready letter sheets, which were produced at the same time, vast supplies of the latter were given to government departments, such as the tax office, for official use. As such the idea of an official stamp was abandoned. A few examples exist postally used which probably originate from the Post Office circulars which were sent out as notification of the new stamps which were being brought into use. Most of the cancelled examples are from trials which were made for cancellation types, inks and experiments with their removal which led to the change from black to red stamps and visa versa for the cancellations.

The VR official is stated as being made from the original master die, however, this can not be the case as this still exists and is housed in the National Postal Museum, London. It is believed that the master for this stamp was produced from the transfer roller used for the production of plate 1 with the stars removed from the top corners as some impressions show traces of these original stars.

See also: list of British postage stamps