FSeven

As others have said, Zed is the callsign for the letter Z in Britain. Here is a list of the NATO phonetic alphabet. In a non-military capacity, it's useful for communicating spelling over the phone. For instance, have you ever been on the phone with a customer service rep and they ask you to spell your last name? Well if you just spell it out by letter, several letters can sound the same: d, t, p. So to ensure spelling is accurate, you would say something like, "D as in Delta, A as in Alpha, N as in November." to spell Dan. Military would just say, "Delta, Alpha, November". As it says at the bottom there exists anomalies/idiosyncracies. To distinguish “Z” from “C” on the phone, it is common practice to say “zed” (an old British phonetic) for “Z”, especially when saying a call sign. “Zed” is shorter (one syllable vs. two for “zulu”.) However, in formal traffic, the ITU (International Telecommunications Union): “ZULU” is more correct and proper. The connection between Zed and Zombie was first made in Shaun of the Dead. It just stuck.