William Lennox is a man who is built on several moral codes such as; leadership, family love and brotherhood. Lennox is also an extremely intelligent and wise individual, who uses his military training for providing his hobby of working with the Autobuts, protecting the world and also battling the Decepticons.
Yet ,despite that he is a man who is built on several morals, he is not showing mercy at all towards his enemies and even nor hesitates to kill them.
In the 5th installment, The Last Knight ,he is the Colonel and the leader of an heroic faction of the TRF organisation ,while the other side is led by the organisation's supreme leader, Santos. Anyway, Lennox in the fifth film is highly different from the Lennox from the first 3 films. He is much more relentless, much more hot temperd, much more violent aganist his enemies, much more tough, and much more determined.