A strikebreaker (sometimes pejoratively called a scab, blackleg, bootlicker, blackguard or knobstick) is a person who works despite an ongoing strike. Strikebreakers may be current employees (union members or not), or new hires, who are hired after or during the strike to keep the organization running. In continuing to work, or taking jobs at a workplace under current strike, strikebreakers are said to "cross picket lines".
Some countries have passed laws outlawing strikebreakers to give more power to trade unions, other countries have passed right-to-work laws which protect strikebreakers.