Wynn or wyn (Ƿ ƿ; also spelled wen, win, ƿynn, ƿyn, ƿen, and ƿin) is a letter of the Old English alphabet, where it is used to represent the sound /w/. It was a continued use of the Anglo-Frisian Futhorc runes. Futhorc was the native alphabet of Old English before the Latin alphabet was adopted, and it was a sibling alphabet to the Younger Futhark alphabet that Old Norse used. Both alphabets come from Elder Futhark.

While the earliest Old English texts represent this phoneme with the digraph ⟨uu⟩, scribes soon revived the rune wynn ᚹ from Old English's native alphabet, Anglo-Frisian Futhorc, for this purpose. It remained a standard letter throughout the Anglo-Saxon era, eventually falling out of use during the Middle English period, circa 1300. In Middle English texts, it was sometimes replaced with ⟨u⟩ or with a ligature form of ⟨uu⟩, until it was replaced with the modern letter ⟨w⟩.

The denotation of the rune is "joy, bliss", known from the Anglo-Saxon rune poems:

ᚹ Ƿenne brūceþ, þe can ƿēana lẏt
sāres and sorge and him sẏlfa hæf
blǣd and blẏsse and eac bẏrga geniht.

— Lines 22–24 in the Anglo-Saxon runic poem

Who uses it knows no pain,
sorrow nor anxiety, and he himself has
prosperity and bliss, and also enough shelter.

— Translation slightly modified from Dickins (1915)

The following wynn and wynn-related characters are in Unicode: