Thermopylae

Thermopylae  is an achievement in Halo: The Master Chief Collection. It is awarded for winning 300 multiplayer games. The achievement is worth 10 gamerscore. It also unlocks the Silver Slayer Nameplate.

Trivia
The name of the achievement is a reference to the Battle of Thermopylae; the 300 wins is a reference to the 300 Spartans who fought in the battle.