Z

More fascinatingiana from wikipedia:

most dialects of English, the letter's name is zed ( /ˈzɛd/) reflecting its derivation from the Greek zeta (see below) but in American English, its name is zee ( /ˈziː/), deriving from a late 17th century English dialectal form. Another English dialectal form is izzard ( /ˈɪzərd/), which dates from the mid-18th century and probably derives from Occitan izèda or the French ézed, for which the Latin form would be *idzēta, perhaps a popular form with an prosthetic vowel.

'Zed', 'Zee' and 'Izzard' hardly exhaust the possibilities for naming this letter, though, do they: I'd like to make a few proposals: zah; ziq; zum; pz; zipproqira; zer; zeb; zay. With a bit of popular usage, one of these could take off. ('I can recite the alphabet, from a to zay' ...)