Ragnok was an orcish warlock of the Shadow Council when warchief, Orgrim Doomhammer, came upon them in a surprise attack and slew nearly every last member, including him.
Shortly after, Gul’dan, his former master, brought him back and placed his spirit, along with his fellow council members, in the decaying bodies of knights of Azeroth.
That is how the Death Knights were born.
The Horde was defeated and the Dark Portal destroyed. Ragnok found himself trapped on Draenor along with Teron Gorefiend and Gaz Soulripper (which rise as Death Knights as well). Teron and other Death Knights convinced Ner’zhul to reopen the portal.
“Pitiful things. I could destroy you with a mere thought! You will come with me to retrieve the Eye or -“
Crown Prince of Lordaeron and Knight of the Silver Hand, he was the son of King Terenas Menethil II and heir to the throne. He was trained as a paladin by Uther the Lightbringer, and had a romantic relationship with the sorceress Jaina Proudmoore.
Taking up the cursed runeblade Frostmourne, Arthas became the most powerful and evil being in Azeroth, he became a Death Knight of the Scourge and led the Undead in destroying Lordaeron, Quel’Thalas and Dalaran. He eventually made his way to the Frozen Throne of Icecrown and merged with the Lich King.
He ruled as Lich King for years and years, Arthas was finally defeated in combat by Highlord Tirion Fordring and his champions of the Light. Cradled by the spirit of his father, Arthas Menethil died, leaving the mantle of the Lich King to be taken by Bolvar Fordragon who would contain the power of the Scourge.
“Wizards of the Kirin Tor! I am Arthas, first of the Lich King’s death knights! I demand that you open your gates and surrender to the might of the Scourge!”