Tav is the last letter of the Hebrew alphabet, and in the older palaeo-Hebrew script that Jewish tradition holds the current square alphabet replaced after the Babylonian exile, discussed elsewhere in this atlas, it was drawn as a simple cross or X shape, a form some scholars connect to the letter's very name, meaning a mark or a signature. That older cross-shaped Tav sits behind a specific rabbinic reading of Ezekiel 9:4, where God instructs an angel to mark the foreheads of the righteous inhabitants of Jerusalem with a tav before judgment falls on the city; the Talmud, at Shabbat 55a, records a discussion of what the mark signified, with one view holding that a tav of ink marked those destined to live and a tav of blood marked those destined to die, and another linking the letter directly to the Hebrew words for life, chayim, and death, tamut, both of which begin with tav. Because Tav is the alphabet's final letter, later Jewish and Christian writers alike have also read it, alongside Aleph as the first, as a natural figure for completeness, an association distinct from, though sometimes compared with, the Alpha and Omega pairing discussed elsewhere in this atlas for Greek.
Tav is also one of the Sefer Yetzirah's seven double letters, discussed elsewhere in this atlas, and a scribe must take the same care distinguishing its hard and soft pronunciations that applies to Beth, Gimel, Daleth, Kaph, Peh and Resh, even though the letter's own graphic history, from a Semitic cross-mark to a modern square-script outline, has changed considerably more than most of its neighbours.