Even moreso than the supergods of yore, it seems hard to believe that the globetrotting, adventure-prone Tintin could possibly be based on a kid of the same age. But in the days before Superman, kids had to be their own heroes.
There are a couple theories as to just who Tintin is based on, but many believe he's the cartoon version of one Palle Huld. See, back in 1928, Huld accepted a Danish newspaper's challenge to complete a trek similar to the one Phileas Fogg traveled in Jules Verne's classic Around the World in 80 Days. The stipulations were harsh: no planes, no chaperones and a misleading time limit of 46 days. Huld braved the foreign-hostile Moscow, a conflict-ridden Manchuria and the unforgiving wasteland of Canada to complete his journey in only 44 days. Since the contest runners were only willing to risk the lives of eligible teenagers, Huld completed his journey at the age of 15. The next year, a Belgian cartoonist named Hergé started drawing the exploits of a globetrotting, adventure-prone boy named Tintin. Those pants can't be a coincidence.
Though Batman has never forgiven the country of Turkey for stealing his name without acknowledging it, he should be careful who he accuses of plagiarism. According to professional dickweed Bob Kane, both of Bruce Wayne's first names came from historical, high-ranking figures. In his book, Kane claimed that Batman's secret identity was coined in honor the Scottish king known as Robert the Bruce, which he combined with Revolutionary War general "Mad" Anthony Wayne. It kind of sounds like the real explanation is "they were originally just random names and later I gave meaning to them," and knowing Kane's bullshittery M.O. that's entirely possible. But for now, we have to accept that a dead guy based a fictional vigilante on two other dead guys.
When discussing the origins for the X-Men, a lot of people fall back on "Professor X and Magneto are really Martin Luther King, Jr. and Malcolm X." It's more than a little problematic, as the X-Men were made to be stand-ins for oppressed minorities of all types, not just African-Americans. It also oversimplifies the real-life figures into inaccurate caricatures; MLK didn't have a teen strikeforce just as Malcolm X wasn't a scheming supervillain.
If you want to talk definite inspirations, there's Yul Brynner as Professor X. Though far removed from the now-classic portrayal by Patrick Stewart, the Magnificent Seven actor had the right severity and credibility to be a mutant headmaster. It helps that he owned his own Shine-O Ball-O.