"And another soul for Sithis."
Dwarven Spiders are small, arachnid-like constructs, and are very common in Dwemer ruins. They will often be found working on rocks or other objects.
Dwarven Spheres are constructs that have proven to be agile fighters, and are much stronger than the smaller Dwarven Spider. Dwarven Spheres patrol ruins in a spherical form until they encounter an opponent.
Dwarven Centurions are the largest and strongest creations the Dwemer left behind. Designed in the form of a large armored warrior, with a hammer on one arm and a spring-loaded spike in the other, they are formidable adversaries that usually serve as the bosses of Dwemer ruins.
Dwarven Ballistae are Dwarven automatons that can be encountered on Solstheim in Dwarven ruins, and are added to radiant dwarven automaton spawns in Skyrim.