Zimmerman?
Beethoven is pretty metal if you ask me, if you get the right recordings. Listen to Falvay, Eder, and Fejervari's recording of his 5th string trio in C minor, first movement (Op. 9 No. 3). Such epic sound achieved with so few instruments.
[EDIT] You can listen to the first quarter of the movement on Naxos by signing up for a free account:
http://www.naxos.com/catalogue/item.asp?item_code=8.572377[/EDIT]
For more big epic sound (and something a little less I-IV-V-Iish than Beethoven) take a look at some of Richard Wagner's overtures, Gustav Holst (The Planets is a must), Gustav Mahler (look up the finale for Symphony No. 8 on youtube, it's nicknamed "Symphony of a Thousand"). Also, Stravinsky really influenced modern action music because of the percussive nature of a lot of his music, especially Rite of Spring.