William M. “Willie” Walsh (b. 1961) is the Chief Executive Officer of International Airlines Group, and also served as CEO of Aer Lingus.

Born in Dublin, Willie joined Aer Lingus as a cadet in 1979 and became a pilot at the age of 17. While advancing to become a Boeing 737 captain, he acquired a Masters in Management and Business Administration from Trinity College, Dublin in 1992. He held various company management positions including chief executive of the then company subsidiary, Futura, from 1998–2000. He returned to Aer Lingus as Chief Operating Officer and became CEO within a year, during a time when the carrier was in financial difficulty. In response to this, Willie made staff cuts, reduced the number of aircraft types and sold non-core assets, reconfiguring Aer Lingus as a low-cost airline in imitation of Ryanair, and succeeded in turning operating profits around.

Willie joined British Airways as CEO in 2005 and immediately faced a number of major challenges, including a global downturn, increased competition, increasing oil prices and taxes. He presided over a period of extensive change for the company and saved the airline from bankruptcy – he reduced the number of managers, increased productivity of engineers, baggage handlers and flight crew, and saw through a dispute with the airline's cabin crew. In 2011, Willie oversaw the merger of British Airways and Iberia to form the new holding company International Consolidated Airlines Group, S.A (IAG) of which he became Chief Executive Officer.

Willie serves as a Member of the Board of Governors of The International Air Transport Association. In 2014 he received the CAPA Aviation Executive of the Year award in recognition of his individual influence on the aviation industry.

Willie was honoured by the British Travel & Hospitality Hall of Fame in 2012.