The pfennig (German: [ˈpfɛnɪç] ^ⓘ; pl. 'pfennigs' or 'pfennige' (listen^ⓘ); symbol pf or ₰) or penny is a former German coin or note, which was an official currency from the 9th century until the introduction of the euro in 2002. While a valuable coin during the Middle Ages, it lost its value through the years and was the minor coin of the Mark currencies in the German Reich, West Germany and East Germany, and the reunified Germany until the introduction of the euro. Pfennig was also the name of the subunit of the Danzig mark (1922–1923) and the Danzig gulden (1923–1939) in the Free City of Danzig (modern Gdańsk, Poland).

The word Pfennig (replacing the denarius or denarius as a low-denomination silver coin) can be traced back to the 8th century and also became known as the Penning, Panni(n)g , Pfenni(n)c, Pfending and by other names, e.g. in Prussia until 1873, Pfenning. The -ing- or -inc suffix was used, in addition to -ung, the formation of affiliation substantives and also appears in other coin denominations, for example in the schilling. Beyond that, its origin has not been clarified, but an early borrowing from the Latin pondus ("weight", cf. pound) is possible. According to an 1848 Leipzig trade lexicon the name pfennig was "originally the general name of every coin in Germany, which is supposed to be derived from the hollow coins or bracteatess, because these had the shape of a pan" (i.e. they were bent)."

The word Pfennig is etymologically related to the English penny, the Swedish penning, which was also model for the Finnish penni (1860–2001), the Estonian penn (1918–1927), the Polish fenig (1917–1918), the Lithuanian word for money pinigai and the pfenig (fening) of Bosnia and Herzegovina (1998–today). The /pf/ rather than /p/ in both pronunciation and spelling is a result of the High German consonant shift or second Germanic sound shift which affected the High German dialects of what is now southern Germany, Switzerland and Austria. High German (and to some extent Central German) dialects form the basis for modern Standard German.

The pfennig was the progenitor of a whole series of later coin denominations, which became parts or multiples of the later pfennig. These include the groschen ("big [pfennig]", from the Latin grossus "big, thick" ), Angster ("narrow [pfennig]", from the Latin angustus "narrow, thin"), Albus ("white [pfennig]", from the Latin albus "white"; initially equivalent to a Groschen), Witte ("white [pfennig]"), Rappen ("pfennig with a raven"), Stäbler ("pfennig with the Basle staff"), Heller ("Haller [pfennig]"), Schwaren ("heavy [pfennig]") etc.

There were also "light pfennigs" (leichte Pfennige), "good pfennigs" (gute Pfennige) or "custom pfennigs" (Zollpfennige), which had this name on the coin. Some types of pfennig were given special names in the vernacular, such as the Erfurt "coffin pfennig" (Sargpfennig).

As a currency sign a variation of the minuscule letter 'd' for 'denarius' in German Kurrent script was modified so the terminal end of the minuscule Kurrent 'd', that trailed at the top of the ascender in an anticlockwise loop, was instead brought down behind the right of the ascender, to form a descender, that hooked clockwise, thus making it a distinct symbol, different from any of the other Kurrent letters in its own right: ₰.

The pfennig symbol has nearly fallen out of use since the 1950s, with the demise and eventual abolition of the Reichsmark with its Reichspfennig, as well as the abolition of Kurrent by the Nazis on 3 January 1941, thus making it increasingly cryptic as familiarity with Kurrent script has decreased since that time. The symbol is encoded in Unicode at U+20B0 ₰ GERMAN PENNY SIGN.

Unicode has U+3338 ㌸ SQUARE PENIHI, a square combination of ペニヒ (penihi), Japanese for "pfennig", for compatibility with earlier Japanese character sets.