Music

Depends on how you define classics, but Sabbath is a must listen, in every incarnation they've had.

I'd suggest Deep Purple as well, maybe some Steppenwolf and Iron Butterfly

You've got bands like Maiden that you have to listen to at least once. Judas Priest is in that category as well, imo.

If you like thrash, then try some exodus, anthrax, megadeth, overkill, kreator and testament

Sepultura is kinda like pantera in that they blend genres a lot, and both are kinda central the the post-80s metal wave.

Fucking motorhead. That's all that needs to be said

Saxon is a cornerstone band. Nwobhm wouldn't have been the same without them

If you want darker/heavier stuff, Death is often cited as the forefront of death metal (though I don't agree). Cannibal Corpse goes back a ways far enough to be a classic band. Dimmu Borgir for the blacker side of things, and I think if you like Bathory, you'll love Dimmu Borgir.

Fuck, I can't not recommend Amon Amarth. Fucking gods of metal.

I'm trying to stick to stuff that's been around long enough to be considered classic, and is also fairly accessible in terms of how far down the rabbit hole you'd be climbing. There's a lot of bands that are essentially formative to one subgenre or another, but don't really hit for most people, or are hard to find to listen to.

Hell, you've got stuff like burzum that essentially founded a subgenre, but kinda suck enough that even some fans of that subgenre don't really listen to more than once.

But, yeah, it really depends on what kind of "classic" you're looking for, and whether you want the stuff that tends to be widely loved, or a more niche experience.