For Greek texts, the fullest list of authors and texts is the TLG Canon, which lists a bit over 12,000 entries. The Canon is free to access, but you'll need to make a (free) account. It doesn't provide full access to the texts, unless you're at an institution that has paid for access.

For Latin-language works, the best I know of is the Bibliotheca Latina IntraText, which is handy but definitely not of the same calibre. Most importantly, it does not include texts/authors that survive only in fragments -- and there are hundreds of fragmentary texts. (Also I see it makes the startling choice of giving Caesar's praenomen as 'Caius'.) I'd love there to be a catalogue done to a more professional standard, but I don't know a better one.