Z (Zeta) is the sixth letter of the Greek alphabet; the related Z is the last letter of the Latin alphabet. In Semitic (Zajin) and Ancient Greek the letter was probably pronounced as /dz/ (as in Italian ZETA, ZERO). In Modern Greek, it is pronounced as /z/, as in English and French. In Etruscan, Z probably symbolized /ts/, in Latin, [dz] (in Latin, the letter appeared only in Greek words, and Z is the only letter besides Y that the Romans took over directly from the Greek, and unlike all other letters not via Etruscan.) In Italian, Z represents two phonemes, namely /ts/ and /dz/; in German, it stands for /ts/; in Castilian it represents /T/ (as English TH in THING), in South American Spanish it stands for /s/ (CAZA and CASA are thus homophonous).
In American English, the letter is named "zee", while in British English the letter is named "zed".