Though not the most physical member of the Bat-Family at times, Alfred is without a doubt one of the most important members. As Batman's confidant, friend, and surrogate father, Alfred has been there through it all for him. No matter what.
Ironically, despite being a simple butler, Alfred's backstory is anything but simple. He is often depicted as an ex-military man, and at times a former member of British Intelligence. As such, he's incredibly smart, well versed in martial arts, and more than willing to use a gun, something Bruce refuses to do.
He has taken out bad guys on his own, both defending his home, and Bruce. Though they do fight occassionally over what is best, when the chips are down, Alfred will always be there for Bruce.