Mallory is the Chairman of the Intelligence and Security Committee, which means he's a bureaucrat telling everyone what to do, even though he has no idea how the business works. Everyone loves bureaucrats.
Initially, Mallory is seen almost as a secondary villain. M sees Mallory as someone against her, and Bond thinks he may even be using Eve to spy on him. However, Mallory is revealed to be on their side as the film progresses. He stands up for M at her hearing, literally throws himself between her and a bullet, and helps Q set up a fake trail for Silva.
Hmm, maybe not all bureaucrats are bad, after all.
After M's death, Bond finds that he now reports to Mallory. But he doesn't call him Mallory. Instead, he says,
MALLORY: Are you ready to get back to work?
BOND: With pleasure, M. With pleasure.
Aha. How convenient that the dude's name starts with M…