The artists who create characters for manga and anime almost always use a real person as a reference for drawing, including their features, hairstyle and skin tones in the cartoon adaptation.
The massive man-eating "Armored Titan" on Attack On Titan is based on MMA fighter Brock Lesnar because of course he is, and the comparison between Rock Lee from Naruto and Bruce Lee is pretty obvious.
But most people are unaware how many of the characters on the sci-fi noir series Cowboy Bebop are based on real actors, including Spike Spiegel who is based on badass Japanese actor Yusaku Matsuda.
The hair, the clothes and the swagger are a perfect fit, and with that in mind who do you think inspired the bounty hunter character Coffee?
That's a no-brainer, Coffee is a ripoff of inspired by Pam Grier, star of the movie Coffy.
The real life inspiration for the High School Of The Dead character Hirano Kohta isn't quite as obvious unless you're an otaku like him- he was drawn to resemble Hellsing creator Hirano Kouta. They changed one letter in his name...nothing obvious about that! *wink*
See 10 Anime Characters You Didn't Know Were Based On Real People here