Bees have to be some of the most ruthless at this. Not only does the queen mate with a dozen or more at a time (she can store the sperm for years afterwards), but the males die of exploded penis as a necessary part of this act while the queen just moves on to the next one. Even if they don’t die in this way, the females kill living and even unhatched drones afterwards. Other examples like the preying mantis are a (actually relatively low) risk that males face, but this is systematic elimination even if they didn’t mate at all.
