Who to meet?

“If you could go back [in time], who would you want to meet?”

~ Toshikazu Kawaguchi, “Before the Coffee Gets Cold”


I have watched movies or read stories in the time travel genre, but the typical topic or question is 'what would you do'? However Kawaguchi's novel asks 'who'. Additionally, the time traveller knows full well beforehand that going back in time will not change the present time at all.

So if you could go back in time just for the sake of meeting a person, who would you want to meet?