The record-holder is the person who has the best mark in a sport right now — the fastest time, the longest jump, the most wins, and so on. You can be the world record-holder or only the school record-holder; the word still fits. It lives most of all in sport, though people stretch it for a joke (“She’s the record-holder for late homework”). Though actually, the person who first set a famous mark years ago may no longer hold it. If someone beats them, they become a former record-holder. That is different from record-breaker, which points at the act of beating the old mark.