A medallist is someone who has won a medal in a competition — gold, silver, or bronze, often at the Olympics or a similar contest. Newsreaders use it constantly during the Games: “She is an Olympic gold medallist.” It is a proud label: you have already won, not merely taken part. This is the British spelling, with two l’s. American English usually writes medalist, one l. Same word, same meaning. Though actually, people mostly pair it with the metal: gold medallist, bronze medallist. Bare “medallist” is fine, but listeners wait for the colour. It does not mean a person who makes medals.