Lego has these, too, of course, but with Lego you at least have the benefit of being able to infinitely combine these parts to build stuff from them. Playmobil is "dumb" in that regard, you can't combine anything except in those ways in which it was specifically designed to be combined.

The real alternative to Lego in my opinion is Duplo, from the same manufacturer. They have no really small parts at all, so these are really good for outside play. But still infinitely combinable.