A collector who is driven to possess every card of a given set, year, team, player, or category. If they collect 2021 Topps Chrome Baseball, the completist will hunt down every card from that checklist – including every base card, parallel, auto, etc. For many collectors, common cards from a given set will have little value. But for a completist, whose aim is to complete each set, the common cards will have significant value, since they cannot complete the set without them.