There have been many striking similarities between Harry Potter and Luke Skywalker of Star Wars. Some of these comparisons are mentioned on this site.
But aside from those mentioned similarities, many things in Harry Potter seem to have been directly copied or plagiarized from Star Wars.
Lord Voldemort is a name so strikingly similar to Lord Vader. The dark lord is a name mentioned in Star Wars to describe Darth Vader and other Sith Lords.
"I'm not turning to the dark side" is a line by Harry Potter towards the end of the first novel. The dark side is a word first mentioned in Star Wars.
Also towards the end of the first novel, Voldemort tells Harry Potter "better save yourself and join me" this sounds strikingly similar to Darth Vader's line to Luke "Join me and together we can end this destructive conflict and bring order to the galaxy."
The replies are more or less the same too. Harry Potter's reply: "NEVER!!!"
Luke Skywalker's reply: "I'll never join you!"
Professor Dumbledore seems to be a copy of Gandalf in appearance and Obi-Wan Kenobi in character.
Gandalf:
Dumbledore:
Peeve Riddles being Dumbledore's former student before changing into Voldemort is an almost exact duplicate of Anakin Skywalker being a Padawan of Obi-Wan Kenobi before turning into Darth Vader. I've even come across sources claiming JK Rowling stole the word "muggle" from another writer's story.
Darth Vader looked like an exactly normal human being as Anakin Skywalker before falling into the lava on the planet Mustaphar. Ever since he has been a monster behind his mask and suit.
The same parallel is that of Tom Riddle looking perfectly normal until he turns into Voldemort and becomes a hideous looking monster.
Some rumors were also spread before the release of the last Harry Potter book that Voldemort was Potter's father. These rumors were most likely a result of JK Rowling making her story so similar to Star Wars theme wise.
Even the marriages of Harry Potter, Ron Weasly and Hermione mirrors that of Luke not marrying the main heroine Leia, though for an entirely different reason.
People would have to read the novels of the Star Wars sequels where Return of the Jedi left off to know what I'm talking about regarding the marriages.
The only people who would disagree with me on these facts would be the die-hard Harry Potter fans.