Ghost recently embarked on its Popestar tour, and people pretty much immediately noticed that there's a woman bassist in the mix. There were rumors that it was Sean Yseult, formerly of White Zombie, but the sleuths over at Blabbermouth seems to have pinned down that it's likely Megan Thomas of the NYC-based Led Zeppelin cover band, Lez Zeppelin.
Much like when we all figured out who Slipknot's bassist was, it's the hand tattoo that gives it away. Look at Thomas' finger tattoo, compared to the Instagram photo below of the bassist signing things for fans. Whoever the hell figured this out… you've got one hell of an eye for detail.