Clockwork Spider (5e Creature)
From D&D Wiki
Tiny construct, unaligned
Damage Vulnerabilities Lighting damage
Spider Climb. The spider can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.
Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., one creature. Hit: 4 (1d4 + 1) piercing damage, and the target must make a DC 13 Constitution saving throw, taking 7 (2d4) poison damage on a failed save, or half as much damage on a successful one.
Tiny, fast, strong (for its size) a clockwork spider is a must-have for any engineer worth his or her salt. From walking up walls to get keys.