Emperor Keikō
Emperor Keikō allegedly had a very large family which consisted of 2 wives, 9 concubines, and more than 80 children (51 of which are listed here). It is now questionable and open to debate though, if these numbers are genuine or not. Some of his listed children might actually be duplicates of the same person. The size of Keikō's family also could have been exaggerated over time through legends and word of mouth stories.