Most notorious badass in history?

[Anomalocaris]

Miyamoto Musashi, Japanese ronin, strategist, philosopher, author, painter, and calligrapher. Undefeated in a record 61 sword duels.

Boru

Important enough to have one of these named after him.

The battleship Musashi was named after the Musashi province in Japan,   Not for Musashi Miyamoto.   All Japanese battleships of WWII era were named for historic provinces in Japan.   No Japanese warships of any kind were ever named for a person.