Strikebreaker

Pinkerton agents escort strikebreakers in Buchtel, Ohio, 1884
Industrial Workers of the World stickerette "Don't Scab"

A strikebreaker (sometimes pejoratively called a scab, blackleg, bootlicker, blackguard or knobstick) is a person who works despite an ongoing strike. Strikebreakers are either workers (union members or not) who cross picket lines to work or workers who were not employed by the company before the dispute but hired after or during the strike to keep the organization running. Some countries have passed laws outlawing strikebreakers to give more power to trade unions, other countries have passed right-to-work laws.