In the last several decades many people including myself have tried to find out where Lucas got his ideas. Lucas helped by leaving plenty of clues.
His villain Darth Vader is patterned after two of the most popular comic book villains of the 60s and early 70s, Doctor Victor Von Doom and Darkseid.
I suspect that Lucas was intentionally drawing the connection between Darth Vader and Doctor Victor Von Doom by giving Darth Vader the same initials as Doom, V and D. Note that Doom has both initials twice. Doctor, d, Victor, v, von, v again and Doom, d again.
Using initials in this way might seem far fetched but Lucas was know to credit his sources with subtle clues like this. Lucas greatly admired a short film 21-87 by Authur Lipsettis. It has been noted that the number on Princes Leia's prison cell on the death star was 2187. Just coincidence, not likely, because the first picture Lucas directed THX 1138 was set in the future, more specifically the year 2187. It should also be mentioned that Lucas admired this Canadian film so much that as a student he created a whole series of films in the same style. So Lucas definitely left clues of this type in his films.
Doctor Doom was horribly disfigured when one of his experiments ended in an explosion. At least this is an origin story I read. There are frequently several versions of an important character's origin in comics. Therefore Doom covered his body in armour and his face in an iron mask. Darth Vader's face and body are similarly disfigured, though not in an experiment, which is why Darth wears a mask and his black outfit.
You may remember that in the "Empire Strikes Back" Darth Vader with his back to the camera takes off his mask and helmet, looks in a mirror, then puts the mask back on. This was a standard routine for Doctor Doom and another way that Lucas announces the source of his character to the comic book savvy.
We can underestimate the influence of Doom because so many other villains have risen to prominence since the original Star Wars movie came out in 1977. But Doctor Doom was for a long time the favorite villain of the Marvel comics superhero universe. Kirby and Stan Lee along with other artists and writers at Marvel comics created the Marvel comics superhero universe in the 1960s.
Darkseid the other character Darth Vader is based on is also credited by Lucus. Lucus does this with the phrase "the dark side of the force." The name Darkseid is pronounced dark side. We have this pronunciation on the authority of Jack Kirby who created Darkseid, and the children's cartoons where Darkseid was a frequent character. Kirby said he patterned Darkseid's face on the look of the moon, so Darkseid is actually a reference to the dark side of the moon.
Jack Kirby was a huge influence on Lucas and Star Wars. Kirby played a big role in creating Doctor Doom, and Kirby alone created Darkseid.
In the early 1970s, Kirby left Marvel and went to D.C. comics to write and draw his own comics. He created three new comics with new heroes: The New Gods, Mister Miracle, and The Forever People. A huge portion of the Star Wars trilogy is based on these three comics. Collectively, these three comics and a little material that Kirby did in other comics is known as the Fourth World.
The heroes in Kirby's Fourth World made use of a mystical power, "the Source." Clearly, the "Source" was a major influence of the "Force" in Star Wars. But as far as I know the source had no dark side. So the forces of evil, lead by Darkseid, had to look elsewhere for their power.
In Star Wars Luke has to struggle with the danger of the dark side of the force. Orion struggles with angry, violent, dark tendencies he has inherited from his father. Of course struggling with evil is such a common theme that not much can be made of this.
As Orion and Luke are similar in being the sons of villains and important champions of the good, I wondered if Luke's last name, Skywalker, was connected to Orion. Of course, Orion is a constellation so he is in the sky, but Orion is the hunter, not the walker.
But I have found what I believe is a connection. Walking in the sky means defying gravity. In heroic literature various forms of flying are common, but walking on something else other than the ground or some solid object is relatively rare. Part of the legend of Orion is that he is the son of Poseidon and therefore has the power to walk on the waves. So I wonder did Orion's wave walking influence the choice of the name Skywalker?
There are other sources for Skywalker, including one that involves Jack Kirby. Kirby drew a comic, Justice Inc. One of the villains was the Sky Walker. The Sky Walker looks like an iron worker with a rivet gun, except he walks in the sky. On the cover of issue #2 the Sky Walker does not seem to be flying, he just stands in mid air firing his rivet gun at the hero.
The Mohawk Native Americans call their men who work as iron workers building tall buildings sky walkers. This comic book villain seems to be a reference to this Mohawk tradition. So in using the name Skywalker Lucas may have been drawing connections to both Kirby in general and Kirby's character Orion in particular.
There was also an article in the New York Times on names in Star Wars that said that sky walker was an appellation of Loki, the Norse God of evil and mischief. Of course, Loki was the chief opponents of Thor in Marvel comics. Kirby drew the first Thor comic book and I believe many more after that. But that could be a coincidence. I might add that the Norse Gods as the were shown in Marvel comics were probably the old gods which Kirby was referring to when he created the New Gods. Kirby was more or less suggesting that the New Gods were post-Ragnarok.
It might be argued the initials for DeSaad are D. S. The Sith name for the Emperor is Darth Sidious, once again the initials are d, s. So both Darth Vader and Darth Sidious may have been named to give credit to their sources in the comic book work of Jack Kirby. The name Vader seems to have been created by dropping the first two letters from the word invader, and Sidious was similarly created by dropping the same two letters from insidious. Lucas, by the way, claims that Vader is Dutch for father, which it is, but it has been pointed out that Darth Vader was named before the plot point that Darth Vader was Luke's father had been decided on.
The third Sith Lord, introduced in the first movie of the prequel was Darth Maul. Darth Maul obviously looks like a devil. The closest Marvel comics has to the devil is Mephisto, which is a traditional nickname for Mephistopheles. Either way, we have both the initials of Darth Maul with the devil Mephisto, or the devil Mephistopheles.
The last Sith Lord, introduced in the second prequel was Darth Tyranus, known the galaxy as Count Dooku. In English adventure and fantasy literature when we hear the word count, we naturally think of Count Dracula. While there is a famous book The Count of Monte Cristo Dracula is far and away the most famous Count of comics, movies, and popular adventure literature. As both Darth and Dracula begin with D the first initial is taken care of.
The last initial is t, which probably a reference to Transylvania, Count Dracula of Transylvania. It seems much less likely that the t is a reference to the first letter of the word tomb, as in the title of the Marvel comic, The Tomb of Dracula. It also seems unlikely that it refers to a Romanian name for Dracula, Tepes, which means impaler. The real Dracula was called Vlad the Impaler, because he impaled his enemies on stakes, very gruesome.
I have just put up a video version of this idea concerning the initials of the four Sith Lords and their sources. It really contains nothing that is not covered here, but if you would like to hear the argument rather than just read it, you might want to watch.
It can be argued that I am stretching things, but note if Lucas was playing a game of using the initials of the Sith Lords to credit at least some of the sources that inspired him then Lucas would also be stretching a little by the time he came to Darth Tyranus, the fourth Sith Lord in his movies.
I have been emphasizing the influence of Kirby and the comics, but of course, Lucas had many other sources beyond comic books and Kirby. Even in the area of comic books I have not touched on the influence of the Green Lantern Core on the Jedi, and no doubt there were other influences as well.
Some people will recognize the sources of Star Wars, others will not. This is not too important to the story. However, the words Star Wars starts with, "A long time ago in a galaxy far, far away...." are more important. Lucas is saying something with these words. When the film came out in the seventies a larger portion of the population may have understood what he meant.
Fairy tales traditionally began with the words, once upon a time, long, long ago, in a kingdom far, far away. Lucas is saying this is a fairy tale. Star Wars has been called space fantasy. It is in some ways a Tolkien fantasy set in space.
Star Wars has many sources, this essay discusses one major source, the comics of Kirby. Still another a major source of Star Wars that seems to have been missed is the second film in Sergio Leone's Once Upon a Time trilogy, Once Upon a Time...The Revolution. Many elements in the plot of Star Wars seems to have come from that film. Check it out.
As you can see, I am into drawing connections between stories. I have written a popular essay on connections between stories in a book written long, long ago, in a land far, far away, the Bible. The essay is about typology connecting the Old and New Testament. If you have a religion allergy do not click here.
Or if you want more Star War stuff, I have calculated the volume, and estimated the floor space of the first Death Star. I estimate the floor space was as large as the surface of the earth and they might have thirty million small rooms per person. The Death Star seems to have been too big.