The maximum player level in Wrath of the Lich King was 80. The expansion raised World of Warcraft’s level cap from 70, established by The Burning Crusade, to 80.
Wrath of the Lich King launched on November 13, 2008, and took players to Northrend, the frozen continent ruled by Arthas, the Lich King. Reaching level 80 marked the start of endgame progression, including heroic dungeons, raids such as Naxxramas and Ulduar, and eventually the assault on Icecrown Citadel.
The expansion also introduced the death knight, World of Warcraft’s first hero class. Death knights began at level 55 rather than level 1, but they still progressed toward the same level-80 cap. Later expansions raised the maximum level again, which can cause confusion when players remember later caps such as 85 in Cataclysm or 90 in Mists of Pandaria. The answer specifically refers to Wrath’s original level range.