Who were the children of Zeus?

Divine Consorts

Hera: Ares, Eileithyia, Eris, and Hebe. Depending on who you reference Hephaestus may also be considered a son of Zeus though he was conceived parthenogenetically (type of asexual reproduction).

Aix: Aegipan

Ananke: Atropos, Clotho, Lachesis (these are the Fates).

Demeter: Persephone

Persephone: Zagreus and Melinoe

Dione: Aphrodite

Eos: Ersa and Carae

Eris: Limos

Leto: Artemis and Apollo

Maia: Hermes

Metis: Athena

Mnemosyne: (original muses) Aoide, Melete, and Mneme (Latter nine) Calliope, Erato, Euterpe, Melpomene, Terpsichore, Thalia, and Urania

Selene: Nemean Lion and Pandia

Themis: Astraea (there's some debate on patronage), Nymphs of Eridanos (there were several), Nemesis, and the Horae (or Hours): Auxo, Carpo, Thalio (all first generation), Dike, Eirene, Eunomia (all second generation), and Pherusa, Euporie, Orthosie (all third generation)

Mortal, Nymphs, and unknown Consorts

Aegina: Aeacus

Alcmene: Heracles (a.k.a Hercules)

Antiope: Amphion and Zethus

Callisto: Arcas

Carme: Britomartis

Danae: Perseus

Elara: Tityas

Electra: Dardanus, Iasion, Harmonia (not to be confused with Ares' daughter)

Europa: Minos, Rhadamanthys, Sarpedon (1st born)

Eurynome: (The Charities or Graces) Aglaea, Euphrosyne, and Thalia

Himalia: KroniOS, SpartaiOS, and Kytos

Iodame: Thebe

Lamia: she had had several children by Zeus, but Hera killed them in a jealous rage (she's the one that devoured children)

Laodamia: Sarpedon (2nd born)

Leda: Pollux (he has a twin brother; Castor, but Zeus is not commonly credited as being the father) and Helen of Troy (formerly Helen of Sparta)

Maera: Locrus

Niobe: Argus and Pelasgus

Olympias: Alexander III of Macedon

Orthreis: Meliteus

Plouto: Tantalus

Podarge: Balius and Xanthus (horses that pulled Achilles chariot)

Pyrrha: Hellen

Semele: Dionysus

Taygete: Lacedaemon

Thalia: Palici (brothers)

Unknown mothers: Ate (the eldest of Zeus' daughters), Litae, and Tyche

I'm i'm fairly certain that's all that are attributed to Zeus, but of course I could've missed a few.