"Headhunter" are industry terms for a third-party recruiter who works on behalf of an employer and seeks out candidates for executive and professional positions on their behalf. Headhunters are generally considered more aggressive than in-house recruiters since they have existing industry experience and contacts. 

Headhunters are usually employed to fill senior management and executive level roles. Headhunters are also used to recruit very specialized individuals. Headhunters both attract candidates, and actively seek them out. To do so, they may network, cultivate relationships with various companies, maintain large databases, purchase company directories or candidate lists and cold call prospective recruits.