According to Hesiod, Theogony927-929, Hephaestus was produced by Hera alone, with no father, see Gantz, p. 74.
According to Hesiod, Theogony886-890, of Zeus' children by his seven wives, Athena was the first to be conceived, but the last to be born; Zeus impregnated Metis then swallowed her, later Zeus himself gave birth to Athena "from his head", see Gantz, pp. 51-52, 83-84.
According to Hesiod, Theogony183-200, Aphrodite was born from Uranus' severed genitals, see Gantz, pp. 99-100.