- A social or business visitor; "the room was a mess because he hadn't expected company"
- The person initiating a telephone call; "there were so many callers that he finally disconnected the telephone"
- The person who convenes a meeting; "who is the caller of this meeting?"
- Someone who proclaims or summons in a loud voice; "the callers were mothers summoning their children home for dinner"
- A person who announces the changes of steps during a dance; "you need a fiddler and a caller for country dancing"
- The bettor in a card game who matches the bet and calls for a show of hands
- An investor who buys a call option