What are some hard metal songs?

I would recommend this

Steel – Charlotte Martin
Titanium – Kraftwerk
Iron – Ensiferum
Cobalt – Colophon

@AstroChuck Are you into any post-transitional metal? Like Bismuth?

@FlyingElephantWithGiganticEars Depends on what you’re really looking for. A lot of different music falls under the “metal” category. There are a lot of sub-genres. And granted, there is a lot of overlap.
If you want some heavy metal, try Metallica or Megadeth.
If you want power metal, try Blind Guardian or Sonata Arctica.
If you want prog metal, try Dream Theater or Rush.
If you want neoclassical metal, try Symphony X or Rhapsody of Fire.
There’s Stoner metal, like Kyuss and Fu Manchu.
There’s speed metal like Judas Priest.

There’s avant-garde metal, and black metal, and viking metal, and industrial metal, and funk metal, and rap metal, and nu-metal, and gothic metal…...

Metallica, Pantera, Megadeth, Van Halen, Judas Priest, Slayer, Anthrax, etc. are some good options. What are you listening to now? What do you like? Do you have a specific sub genre of metal in mind?

Start with Sabbath first.
Then explore each sub-genre: Death, doom/stoner, Black, Grind, Thrash, etc.

Why hasn’t anyone mentioned Avenged Sevenfold?

@Fred931 Because A7X isn’t very big within the general arena of metal. It isn’t nearly as big as several bands from the 60s, 70s, 80s and 90s. I don’t know about other people, but I don’t like too much metal from the 2000s.

There are also DevilDriver, Children of Bodom, and Scissorfight. May not be the best, but at least it’s different.

I find myself really enjoying the symphonic/goth metal groups, so I just raided my Pandora station for all of the bands that match that description for you: Lacuna Coil, In Tenebris, Mortal Love, Epica, Leaves’ Eyes, Nightwish, Within Temptation, Sirenia, Theatre of Tragedy, Xandra, The Crest, Tristania, Octavia Sperati, The Gathering, Edenbridge, and Tiamat.

The uniting feature of all these groups is that you get really hard (goth/doom/death) metal music contrasting with female (often professionally trained sopranos) vocalists.

Slayer!

Progenies of the Great Apocalypse by Dimmu Borgir

You might also try listening to Dream theater, Black Label Society, Megadeth, Iron Maiden, Queensryche, Pagan’s Mind, Evergrey, Nightwish and Soilwork.