Black Sails is a popular TV show based on Robert Louis Stevenson's Treasure Island, acting as a prequel. Due to the iconic fictional source material, humanity's fascination with real-world pirates, and a new age of cinema where even The Lord of the Rings has to be gritty and realistic, the show presents a mix of characters based on stylized fictional pirates and characters based on renowned pirates of the real world.
As with shows like Vikings, historical accuracy can sometimes make way for some creative license, the same way regular shows often sacrifice character for the sake of the story. It's interesting to see how they tweaked the characters, and it gives you some insight into the adaptation process. The truth of history is always uglier...
Captain Flint (Fictional)
Captain Flint, played by thespian and former Bond villain Toby Stephens, leads the show's impressive cast and drives the prequel's story toward its inevitable conclusion. The character is based on the one created by Robert Louis Stevenson, who is alluded to, though he never actually appears in the book. The show's look for the character serves as a prequel in itself to the heavily bearded and decorated look previous adaptations have used for older versions of the character.
John Silver (Fictional)
Long John Silver is one of the most famous pirates of all time, despite being fictional. The show could have taken him in various directions, as it explored a lesser-known period of his fictional life. The show's version of the character could evolve into something like the original, but it tones down a lot of the look.
The original character was based on a friend of Stevenson's, who was described as "...a great, glowing, massive-shouldered fellow with a big red beard and a crutch; jovial, astoundingly clever, and with a laugh that rolled like music; he had an unimaginable fire and vitality; he swept one off one's feet". As well as the iconic peg leg he always had his trusty parrot atop his shoulder.
Ben Gunn (Fictional)
What we know of Ben Gunn's appearance in the book is mainly a product of his being marooned on Treasure Island for three years. The show's version of the character is a lot younger with incredibly resilient skin given the circumstances, but he matches the spent-too-long-in-Jumanji look of the original.
Billy Bones (Fictional)
Billy Bones is a character heavily featured at the beginning of Robert Louis Stevenson's novel. He is depicted as a stoat, stern, weather-beaten, and incredibly muscular man. He is an intimidating-looking man with a strong jaw and chin and a scarred face, not much of a looker either.
The show's version, played by Tom Hopper, seems a bit lankier and easier on the eye than the original, but he has the brawn and the steel gaze, so he works as a younger interpretation of the character.
Blackbeard (Real)
Blackbeard is another of the most famous pirates of all time, possibly the most famous. There are a lot of myths surrounding the figure, but he was a real pirate, an Englishman named Edward Teach. He is played by Ray Stevenson in the show, and, while they pay homage to his personality and black beard, the real beard was less bushy and hung in thick pointed braids. Real pirates often dressed more grandly and less scruffily than fiction likes to portray.
Captain Charles Vane (Real)
Charles Vane was another real-world pirate, also probably English, though he and his exploits are less well-known. The show's version of the character, played by Zach McGowan, looks very different from the real man. While they both had long hair, he didn't share Zach's slender build, and his long hair was curly and messy rather than the straight braids seen in the show.
Rackham (Real)
John Rackham, more commonly known as Calico Jack, was another real English pirate whose exploits were well-documented. He is most famous for employing female crew members, most notably Anne Bonny. While the show's version of the character, played by Toby Schmidtz, is usually wearing a very accurate costume, he lacks the real Calico Jack's large chiseled features and substantial nose.
Anne Bonny (Real)
Anne Bonny was a real Irish pirate and probably the most famous female pirate of all time to come out of the West. Known for being a lover and crew member of Calico Jack, her execution was stayed due to her being pregnant, and it's unknown what ultimately became of her...
The show got the costume and hair right, but the real Anne Bonny didn't share Clara Padget's soft, slender features and build. The real Anne had round cheeks and an awkward, lanky frame, and is often depicted with a lazy eye, none of which made her any less badass.
Benjamin Hornigold (Real)
Benjamin Hornigold's piracy days were shortlived—another aspect of piracy that wasn't uncommon that fiction often overlooks—but they were a busy six years. The show's version of the character, played by Patrick Lyster, seems accurate enough, except that the real Benjamin Hornigold died at 39. Patrick Lyster didn't appear to be in his 30s in the show.
Woodes Rogers (Real)
Woodes Rogers was a real man, and, as his occupation wasn't kept off the books, his adventures are well documented. The show's version of the character, played by Luke Roberts, is one of the show's most accurate looking characters, from the hair to the high collars and scarves to the way he holds himself.
As with most of the actors on this list, Roberts is better looking than the character he plays, but, if actors had to match the looks of historical figures Leonardo DiCaprio wouldn't be able to play anyone. Imagine The Wolf of Wall Street if its version of Jordan Belfort actually looked like the real Jordan Belfort... it wouldn't have been nearly as marketable.