Soon, “Guitar Hero: Aerosmith” won’t be alone; next up is “Guitar Hero: Metallica.”

GameSpot reports that analyst firm Wedbush Morgan Securities discovered the new Guitar Hero while examining a recent SEC document from “Guitar Hero” publisher Activision.

“Metallica” is due to arrive on multiple platforms before the end of the company’s current fiscal year, March 31, 2009. No details on the game itself are available.

According to MTV’s Rhythm Game Track Finder, Metallica has  been featured in “Rock Band” and “Guitar Hero III.”

Last November, MTV senior VP of home entertainment Paul DeGooye said Metallica would be debuting their next single through “Rock Band.” MTV Multiplayer has contacted all parties involved to see if this news changes that.

Readers, what do you make of today’s leak? Are you excited about Activision’s decision to produce multiple music games based on single artists?