John Michael Whelan is the 18th General Secretary of the British trade union ASLEF, a position he has held since 2011.

The Associated Society of Locomotive Engineers and Firemen (ASLEF) is a British trade union representing drivers of trains including services such as the London Underground (Tube). It is part of the International Transport Workers' Federation and the European Transport Workers' Federation. At the end of 2019 ASLEF had 24,479 members. Mick Whelan became its General Secretary in 2011.