How do you make the list? Well, be well-known, be capable of ending fights (win sport fights by stoppage, not decision), and be a proven commodity. And since this is martial arts, we're not necessarily talking about people that are deadly, just those that could be.
Here goes.
Fedor Emelianenko
When talk turns to modern day warriors, it usually ends up including combat athletes. Enter Fedor Emelianenko, a Russian MMA Heavyweight and World Combat Sambo Champion that is widely considered to be the greatest heavyweight fighter in MMA history. To date, he has only lost one bout (30-1 record) and has stopped, either via submission or knockout, more than two thirds of his opponents. His physical strength is legendary, as is his well-roundedness.In the end, don't let Emelianenko's calm demeanor fool you; he's scary lethal.
Helio Gracie
In 1914, Kodokan Judo master Mitsuyo Maeda taught Brazil’s Carlos Gracie the Japanese art of judo in appreciation of his father's help in business. Carlos in turn taught his brothers. Helio, the youngest and frailest of the family, was unable to make judo work for him due to strength disadvantages. Thus, he began to refine some of judo's teaching to utilize leverage more and strength less. The art he invented eventually became known as Brazilian Jiu Jitsu.Later, Helio would defeat larger opponents in a precursor to modern day MMA by utilizing the submission holds that make BJJ what it is. Let's face it: if knowledge is power than that makes Helio Gracie as powerful and deadly as they come.
Rickson Gracie
Simply put, some espouse that Rickson Gracie (son of Helio) has never lost a Brazilian Jiu Jitsu, MMA, or street fighting match. In fact, Rickson himself claims over 400 victories. Though this is disputed by some, what we do know is that even his brother Renzo has verbalized the belief that Rickson is the best fighter to come out of the first family of MMA and Brazilian Jiu Jitsu. And when you're considered the best Gracie submission fighter ever, that may just make you the best BJJ fighter period.That's deadly.
Masahiko Kimura
By competing with bravery against Japanese Judoka Masahiko Kimura in defeat, Helio Gracie won a morale battle due to his size and the fact that he refused to tap. But when you consider the fact that Kimura actually won the fight with a submission move that would be eventually named after him (the Kimura), it's certainly hard to keep him off this list.At age 18, Kimura became the youngest godan ever (5th degree black belt) when he defeated eight straight opponents at the Kodokan, and it is believed that he only lost four judo matches during his career. He also trained in both Shotokan and Goju-ryu karate. Simply put, Kimura was one of the greatest judo fighters of all-time. He was as deadly as they come.
Saigo Takamori
Though many of the greatest of samurai (Japanese warrior class) remain nameless, the film The Last Samurai offered a glimpse into Saigo's last days. He built himself from a low ranking samurai official to a man whose opinion influenced the Japanese Imperial Court. He also led the imperial forces to victory in the Boshin War, eventually accepting the surrender of Edo Castle from Katsu Kaishu; thus, proving his mettle in battle.However, Saigo is best known for leading 40,000 samurai against 300,000 Imperial troops in an effort to preserve the samurai way. When he and his brethren fell at the Battle of Shiroyama, all samurai fell with him. Saigo makes the list as a noteworthy representative of a breed that fought with honor.

