Ants keep slaves. Certain species, the so-called sanguinary ants in particular. raid the nests of other ant tribes, kill the queen, and kidnap many of the workers. The workers are brought back to the captors hive, where they are coerced into performing menial tasks.
Spiders
Spiders never spin a web in structures made of chestnut wood. That is why so many European Chateaux were built with chestnut beams -- spiders webs on a 50-foot beamed ceiling can be hard to clean.
Fleas
Bees
Bees work. Males remain in the hive and literally do nothing, their only mission in life being to fertilize the queen bee on her maiden flight. For this purpose literally thousands of males are hatched, out of which only one or two mate with the queen. After they have served their function, the males are not allowed back into the hive but are left outside, where they starve to death.