Bio: Bill Waring is a meek and harmless law student who is a victim of bullies. He never does much about this, but when his father is killed for giving evidence to the D.A. about an alliance between the Mob and a prominent local politician, Bill swears vengeance. He travels around the world, learning the proper skills to avenge his father and kill criminals. (Capturing the bad guys is not a high priority for the Challenger, who is very much in the Killer Vigilante mode.) The Challenger learns jiu-jitsu in Japan. He learns chemistry in Tibet (Tibet???). He learns nerve control in India, so that he is immune to pain. He learns swordsmanship in Paris and marksmanship in Germany. He learns how to fly in England. He learns how to box. He learns every imaginable skill which might help him in the war against crime. And then he returns to America and avenges his father, after which he takes on various other criminals.
In addition to his various skills, the Challenger is considerably more experienced in the fantastic and uncanny than other, similar characters. A text piece mentioned that he he spent several months in Central Africa and Abyssinia, where he encountered a lost colony of Latin-speaking Romans.