Just a fun discussion and purely that. To subjective so no real right or wrong answer! Time frame 1900-2019. [b]Reasons documented proof and traceable records.[/b] So NO screaming abuse and kids shouting - “Bruce Lee was the best fighter on the planet.” Crap without any documented proof of title defenses (against other world level athletes) or tangible and traceable bouts. He was an amazing fighter and martial artist but greatest is way to hard to prove in his case. Also keep in mind - NOT “influential martial artist!” As yes Bruce Lee would make a fine entry. [b]Any style goes. [/b] Boxer, bare knuckle (king of gypsies) or underground boxers, (if traceable record) So no Charlie Zelanoff doesn’t count! - Vale Tudo, MMA, 8 point Muai Thai, karate, kung fu, grappling, classic jiu jitsu / BJJ ect ect for the above time frame. Keep it clean and remember this is for fun and sheer discussion value. Also remember how styles may match up. Would a boxer succeed in 8 point Muai Thai? Could a master at kung fu survive a top level grappler and a prolonged ground game? Questions and mature discussion!! BEST fighter ever. GO.