So nematodes (round worms), cestodes (tapeworms), trematodes (flukes). Do not multiply in human hosts cf parasitic protozoa. Multiply through reinfection though! Most have life cycle in other hosts.
Mostly intestinal tapeworms, not that important, but Taenia solium eggs cause cysticercosis.
Hydatid cysts (larval stage of Echinococcus granulosus) are life threatening. Adult stage found only in dogs.
Complex life cycles involving snails. Cysts are ingested, with exception of schistosomiasis, where larvae (cercariae) penetrate skin. Migration within the body is a feature, where they end up causes problems even if it’s a dead end for the organism.