Z-list describes a person — usually someone in show business — who is at the very bottom of the fame ladder. It is an adjective: a Z-list actor, a Z-list celebrity, a Z-list party. The word comes from the way English speakers rank famous people by letters. An A-list actor is a big star, the kind who can carry a film. B-list is one step down, and so on. Z is the last letter of the alphabet, so Z-list means "as low as it goes". It is not a real ranking that anyone keeps in an office somewhere; it is a joke that people now use seriously. When you say Z-list, you are saying something unkind, and you mean to. There are two flavours of unkind here, and they are worth keeping apart. Sometimes it just means "hardly famous at all" — a Z-list singer plays small rooms and nobody outside her city knows her. But more often it carries a sharper meaning: this person IS famous, quite famous even, but for nothing worth being famous for. They were on a reality show. They married someone important. They said something stupid online and everyone shared it. The complaint is not about the size of the fame but about the emptiness of it. British newspapers and gossip writers use this word a lot; it feels very British, though people elsewhere understand it. It is informal. Do not use it in a school essay or a news report, and be careful using it about a real person you know — it is close to an insult. English speakers also stretch the pattern to things that are not people at all: a Z-list university, a Z-list hotel, a Z-list film festival. Anywhere there is a ranking, someone will joke about the Z-list end of it.