Sleep Token are one of the fastest-growing bands in heavy music that we've seen in quite a few years, but they've done a good job maintaining anonymity. However, people on the internet have some theories about the real identities of the members, so let's dive in to what they're saying.

Just to put into perspective how quickly Sleep Token are blowing up — they had less than 300,000 monthly listeners on Spotify at the beginning of January, and as of today (Jan. 31) they have over 1.58 million. That's a pretty massive increase in size for a fanbase in such a short period of time.

They dropped a couple of singles throughout the month, including the wildly popular "The Summoning," and apparently have an album titled Take Me Back to Eden coming out soon [via Genius]. But other than that, all we know is that the group is led by a frontman named Vessel. Like Slipknot, Ghost and other masked bands before them, part of the allure about Sleep Token is that no one really knows who's behind the masks.

But as history has shown, the identities are revealed eventually. And fans of the rising band are working hard to try to uncover them.

One of the theories people have come up with is that Sleep Token are Don Broco, and they've supported the claim by noting that both groups don't release music or tour at the same time, and that Vessel's voice sounds like Don Broco singer Rob Damiani.

Others are making jokes about their identities — for example, implying that Panic! At the Disco broke up because Brendon Urie is Vessel, or that Andrew W.K. is the singer behind the mask.

Read some of the tweets below.

Sleep Token's next performance is scheduled for April 8 at the Takedown Festival in Portsmouth, U.K. See the rest of the dates and get tickets here.

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