Papyrus 121, also known as P. Oxy. LXXI 4805, is an early copy of the New Testament in Greek. It is a papyrus manuscript of the Gospel of John in a fragmentary condition. It is designated by the siglum in the Gregory-Aland numbering of New Testament manuscripts. The surviving texts of John are only fragments of verses 19:17-18,25-26. Using the study of comparative writing styles (palaeography), it has been assigned to the 3rd century by the INTF.
The manuscript currently is housed at the Papyrology Rooms of the Sackler Library at Oxford with the shelf number P. Oxy. 4805.
The manuscript is written irregular, spaces between letters are not equal. Though the text is very small, it contains two of the nomina sacra: and (dative case from ). Above letter iota two dots (diaeresis). On page recto, in lower line, from the left a scribe did not use letter iota in word úñù (and), though inserted diaeresis above letter alpha. Possibly it is a scribal error.
The Greek text of the codex is too brief to determine its textual character. It can not be placed to any of Categories of New Testament manuscripts. It contains only 20 letters on recto, and 18 letters on verso.
Missing letters are in red; extant letters in black.