Gary Oldman is probably one of the most underrated actors in Hollywood.
Like Johhny Depp and Daniel Day-Lewis (both also in The Acting Hall of Fame), Oldman loves going for those weird eccentric roles. He doesn't mind playing minor roles, or even cameos. Gary Oldman is the ultimate team player. Even if he is a better actor than all the other actors in the film combined, he will never hog the spotlight. He doesn't need to.
Director Christopher Nolan should be credited for his excellent casting choice. The no-nonsense yet totally nice guy-demeanor of Sgt. Jim Gordon was captured perfectly by Oldman. But the best part was that Oldman's facial hair made him invisible. A friend of mine never knew it was Gary Oldman until the end credits. I wouldn't have noticed him too, had I not known the fact beforehand. And even if you did know beforehand that Oldman would play Gordon, you'd forget about it as soon as Gary Oldman appears onscreen. Gary Oldman ceases to be Gary Oldman and becomes Jim Gordon.
Perhaps it would be best if we ended this with a quote from Christopher Nolan himself.
With a great actor like Oldman, it really doesn’t faze him to be looking at nothing but a bunch of grips and electricians. He’s able to ignore the green screen and tap into the psychological reality of the situation.
*some info and pic from DGA Quarterly