ShadeStrider

At the end of Resident Evil 4, compared to "It", Krauser, and many others, Osmund Saddler is an easy boss.

But I don't find it an anticlimactic fight: I find it representative of Saddler as a character: in the end, to get to where he was, he had to manipulate people. He manipulated the village people and their leader, he manipulated Salazar by using his sense of guilt against him, and he manipulated Luis Sera into researching for him.

But at the end, when he faces Leon and Ada for the last time, there is no one left to manipulate: The Ganados are few in number, Ashley and Leon are no longer Las Plagas hosts (Thanks to Sera coming to his senses), and all of Saddler's subordinates are dead. And without the power of those he manipulated, he was considerably weaker.

I bet Krauser could have taken down Saddler easily... If he wasn't so busy fighting off Leon and Ada.

In a sense, if it weren't for Sera, Krauser losing to Leon would have worked in Saddler's favor, since he'd have two more people to manipulate.