So zed is British and zee is American, yes? Well, that might be the case today, but once upon a time things were quite different. Historically, both zed and zee were used pretty much interchangeably in both British and American English, alongside a whole host of other more outlandish names for the last (or rather, second last) letter of the alphabet, like izzard, uzzard, zad, shard and, our personal favorite, ezod.
Of the two we’re talking about here, however, zed is by far the oldest, and takes its name via French and Latin from that of its Greek equivalent, zeta. Zed first appeared in print in the early 1400s, in a Middle English document that fairly straightforwardly described it as “þe laste lettre of þe a b c”—which is considerably nicer than what William Shakespeare had to say about it.
More, here.
