Led Zeppelin are back for the third time in the Ultimate Classic Rock Hall of Fame semifinals. And this time, with no Rod Stewart in sight, do they have a chance of getting in?

They certainly deserve a spot. There's only a handful of bands about which you can say, with no exaggeration, that they helped shaped rock history. Led Zeppelin tore through the '70s with little regard for convention, volume or decency. They pretty much invented the concept of rock gods. Oh yeah, their music was pretty awesome too.

On the other hand, the Doobie Brothers started the '70s as a guitar-based rock band that made music that sounded pretty damn good while you were sipping some cold, tasty beverages. But after a lineup change mid-decade, singer Michael McDonald steered them toward an R&B-inspired pop career that led to multi-platinum records by the end of the decade.

Every month, the readers of Ultimate Classic Rock will decide which of eight legendary artists or bands will be remembered for their contributions to the genre.

So who will it be? One of rock 'n' roll's most powerful bands or a group that transformed itself into one of pop music's biggest acts of the '70s?

The semifinals competition ends Sunday, Dec. 22, at 11:59 PM EST and the winner will be announced on Jan. 6. Be sure to read our official rules here. Vote now!