Thief (5e Creature)
From D&D Wiki
Medium humanoid (any race), any alignment
Sneak Attack (1/Turn). The thief deals an extra 3 (1d6) damage when it hits a target with a weapon attack and has advantage on the attack roll, or when the target is within 5 ft. of an ally of the thief that isn't incapacitated and the thief doesn't have disadvantage on the attack roll.
Dagger. Melee or Ranged Weapon Attack: +4 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 4 (1d4 + 2) piercing damage.
Thieves specialize in stealing and breaking into buildings. They fare better picking locks than fights, and tend to turn to combat only as a last resort.