Who are the characters shown here, standing behind Theoden?
I don't know, and can't figure out who they are from the character list on The Two Towers (film) nor after a bunch of googling. This question is specifically for the above scene in Jackson's movie adaptation. Thanks so much.
Edit: This is of course during the battle at Helm's Deep. Thanks to any LotR buffs who might know. Someone sent this around at work and issued a challenge to name the three characters. All in good fun, and happy Friday!
Update: I rewatched TTT and took some video clips, it's a little easier to see the actors, see this, this, and this. Thanks @Valorum for figuring out the character on the right is Gamling, but the guy on the left is still a mystery! He has no speaking lines. movie-dude refers to him as an unnamed extra (see #46). My wife and I went down the list of actors, including those uncredited, and couldn't pick him out. The hunt continues!
Update 2: I got confirmation from a reliable source that the guy on the right in the picture is Gamling (actor Bruce Hopkins). It's much easier to tell if you watch the video I linked (Theoden says "Give them a volley" and then you see a profile shot of Gamling shouting "Fire!"). Even though the guy on the left looks a lot like the picture of Gamling in @Valorum's answer, he is a different actor.