A Ruin Kobold Trooper (ルインコボルド・トルーパー, Ruin Koborudo Torūpā?) is a type of monster that is found in the 1st Floor Labyrinth in Sword Art Online. It is a humanoid-type monster that is capable of using Sword Skills and wielding weapons.
It is similar to the Ruin Kobold Sentinel, but weaker and, unlike the Sentinels, the Ruin Kobold Troopers respawn at a set rate in the Labyrinth. It takes Asuna three hits of «Linear» to defeat a Trooper.
They are first encountered when Kirito first meets Asuna. The first one depicted on the eighteenth level of the Labyrinth is «Level 6» and wields a hand axe.