The Greek gods
Greek mythology has its own site: thegreekgods.org, with a family tree from Chaos to the Olympians and the Muses and a page for each figure.
It is where this site's family-graph idea began. Here, the Roman pages link to their Greek counterparts there, with a note that the two are separate cults.
Compare tool: Greek deities are not included in the cross-culture comparison, but you can set them beside any of the eleven traditions here by reading both pages.