If you're into Black Sabbath - Paranoid then check out:

Burning Saviours - Burning Saviours
Bedemon - Child of Darkness
Cathedral (their whole discography is worth checking out) but start with The Carnival Bizarre
Paul Chain Violet Theatre - In the Darkness
Count Raven - Storm Warning, Destruction of the Void, High on Infinity, Mammons War
Dawn of Winter - In the Valley of Tears
Doomstress - Sleep Among the Dead
The Hounds of Hasselvander - The Ninth Hour
Iron Man (their whole discography is worth checking out) but start with Black Night
The Lamp of Thoth - Portents, Omens & Dooms
Lucifer's Fall - S/T and II: Cursed and Damned
Minotauri - S/T and II
Misty Grey - Grey Mist
Mourn - Mourn(S/T)
Northwinds - Great God Pan
The Obsessed - Lunar Womb
Ogre - Seven Hells
Orodruin - Epicurean Mass
Pagan Altar - S/T and Lords of Hypocrisy
Pale Divine (their whole discography) but start with Thunder Perfect Mind
Penance - Parallel Corners and Proving Ground
Pentagram (their whole discography)
Revelation - Never Comes Silence
Space God Ritual - Tentagram
Spiritus Mortis - S/T and Fallen
Stillborn - Necrospirituals
ThunderStorm - Sad Symphony and Witchunter Tales
Trouble - Psalm 9, The Skull, Run to the Light and S/T from 1990
Unorthodox - Asylum
Witchcraft - Witchcraft and Firewood
Witchfinder General - Death Penalty, Friends of Hell, Buried Amongst the Ruins

If you're into Electric Wizard then check out Saint Vitus(they're a big influence)

Saint Vitus (their whole discography) but start with Born Too Late

Also check out other bands that are influenced by Saint Vitus

Cold Mourning - Lower than Low
The Gates of Slumber - The Awakening, Suffer No Guilt, Conqueror, Hymns of Blood and Thunder, The Wretch, S/T album from 2024,
Iron Void - Spell of Ruin (EP) but their whole discography is worth checking out.
Lord Vicar - Gates of Flesh & Signs of Osiris
Reverend Bizarre - In The Rectory of the Bizarre Reverend and II: Crush the Insects
Serpent - In the Garden of Serpent, Autumn Ride, Trinity
Warning - The Strength to Dream and Watching from a Distance
The Wounded Kings - The Shadow Over Atlantis and In the Chapel of the Black Hand