Mastodon, which plays White Oak Music Hall on May 9, is one of the hottest bands on the metal scene. If only Mastodon were actually a metal band.

Mastodon has sold out arenas and festivals around the globe. Its last three records have peaked inside the Billboard Top 10. Mastodon even brought home its first-ever Grammy Award earlier this year.

By any measure, the Atlanta-based quartet is universally regarded among the preeminent metal bands on the planet. This is all well and good, save for one thing – Mastodon, which plays White Oak Music Hall on Wednesday night, doesn’t really consider itself a metal band anymore.

“We really don’t think of ourselves that way, but of course, when you walk into a record label in Hollywood and go to where the genres are listed, we get why categories exist,” Mastodon bassist/co-vocalist Troy Sanders said on a recent phone call. “And, for a while, it certainly made sense.”

Early Mastodon was far heavier than its modern-day counterpart, so Sanders and his bandmates certainly understand their reputation as a metal outfit. Nor are they ashamed of such a designation.

Rather, Sanders and Co. simply feel they’ve evolved to a point where labeling them under any particular genre would be unfair. And after nearly 20 years in the rock game, it’s a courtesy they’ve certainly earned.

“Our earlier music was more aggressive and abrasive with extreme vocals, so our first few records certainly set us up,” Sanders said, with regard to the band’s reputation. “We did tours supporting Slayer, Metallica, Ozzfest; we’ve gotten to tour with all our metal heroes. So that’s where the whole heavy metal tag kinda stuck, and that’s okay. We get it.”

In recent years, the band has experimented with a number of genres, which has culminated in one of the more unique catalogs in rock music.

From hard rock to prog to experimental, Mastodon tried new things, even at the risk of running off fans who came to love the band for one particular genre. Most stuck around to see what Mastodon did next, and the band’s approach has earned it new fans.

“Every time out, we try to write more epic songs, but it’s never a spoken thing,” Sanders said. “It’s incredible, in that it just naturally flows through whatever songwriting we have going on at the time. It comes naturally, and it comes from within, out through the pores, into the instrument and out through the speakers. We gravitate toward what we like, so we build on that until the songs are created. When it’s done over and over, then we have an album. But I can’t over-emphasize how I feel about how authentic our music is. We never talk like, ‘should we stay inside the box or branch out.’ We don’t talk like that. There are no rules or parameters. We treat it very openly, and we let what happens happen.”

Hard rock is a genre dominated by strong, tough types. These are not typically folks who care much for mainstream adoration, much less awards. And, yet, when Mastodon won its first ever Grammy earlier this year for Best Metal Performance (the band had previously been nominated four times), Sanders admits he and his bandmates were quite touched at receiving such a noteworthy accolade.

“We’re very aware of how people feel about the Grammys, both the pros and cons,” Sanders said. “Sure, rock has dwindled and metal covers such a wide range of music (from an awards perspective), but overall, we are a band of optimists and positive people. We were thrilled the previous times we were nominated, and to have finally gotten that recognition from the body of the Grammy organization, to have worked as hard as we did for 18 years leading up to it, we were very proud of that. We felt we also were able to represent the dozens and dozens of heavy bands we tour with. In a way, our win means that, to a small degree, we all win.”

Mastodon’s show is scheduled for 7 p.m. (doors open) on Wednesday, May 9 at White Oak Music Hall, 2915 North Main. For information, call 713-237-0370 or visit whiteoakmusichall.com. $29.50, plus fees. All ages show.