According to Hesiod, Theogony927–929, Hephaestus was produced by Hera alone, with no father, see Gantz, p. 74.
According to Hesiod's 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.