Usagi Yojimbo action figure in the '89 series and an updated, more comic accurate version from the early 2000s toyline.
Although I picked up the 2000s Usagi off the shelves when new, I still only vaguely understood his universe and wasn't 'officially' collecting TMNT toys anyways. I later acquired the original Usagi action figure and even Space Usagi, and finally began reading the entire collected series in graphic novel form.
That's where I learned about the rhino samurai Murakami Gennosuke aka 'Gen', and later discovered he too had an action figure!
My Gen didn't have the twin katana he was originally released with, but I can probably dig up at least one out my random accessories bag.