There's hardly any festivals where I’m from but I have seen:
Deathriders (x2), Destruction (x3), Whiplash (x3), Exumer, Sadistic Intent (x2), Morbid Saint (x3), Merciless Death (x4), Onslaught, Artillery, Anthrax (x2), Exodus (x3), King Diamond (x2), Possessed (x5), Satan (x2), Grim Reaper (x3), Exciter (x4), Atrophy, Warbringer (x3), Fueled By Fire (x5), Metal Church (x2), Armored Saint, Excel (x7), Deathhammer, Death Angel, Diamond Head, Metallica (FREE SHOW), Kreator (x3), Obituary (x2), Midnight, Power Trip (x2), Wehrmacht, Witchaven (x3), Suicidal Tendencies (FREE SHOW), Suffocation, Morbid Angel, Antichrist, Hirax (x6), Sacred Reich (x2), Doro (x2), Evildead (x6), D.R.I. (x5), Toxic Holocaust, Nuclear Assault, Bonded By Blood, Skeletal Remains (x2), Nasty Savage (x3), Dr. Know, Nocturnus A.D., Razor, Demolition Hammer (x2), Cryptic Slaughter, Final Conflict, Vio-Lence (x4), Flotsam and Jetsam (x2), Repulsion, Massacre, Iron Maiden, Toxik, Cavalera (Sepultura; x3), Mercyful Fate, Candlemass, Détente, Dark Angel (x2), Autopsy, Conflict, The Exploited, GBH, Overkill, Heathen, Left to Die (Fuck the venue), Kings of Thrash (Ft. Dave Ellefson, Chris Poland, Jeff Young), Lizzy Borden