The Lord of the Rings: The Return of The King
As of May 01st 2018, Black Panther is the highest grossing superhero movie in America [& the third highest grossing movie ever]Worldwide box office, The Avengers is the highest grossing superhero movie followed by Avengers Age of Ultron & Black Panther.
The sentence should be hyphenated thus: 'It is the highest-grossing movie of the year.' The adjective is 'highest-grossing' - the superlative form of 'high-grossing'.
James Cameron's Avatar is the highest grossing movie worldwide w/ $2,787,965,087.
Harry Potter and the Deathly Hallows Part Two - third highest grossing movie ever.Lord of the Rings: Return of the King - fourth highest grossing movie ever.Lord of the Rings: Return of the King was the third highest grossing movie until the release of Harry Potter and the Deathly Hallows Part Two which overtook it.
Avatar is the highest grossing Oscar winning movie of all time worldwide.Avatar is also the highest grossing Oscar winner domestically because the highest grossing movie, Star Wars: The Force Awakens did not win in the 5 Oscar categories in was nominated for.When adjusted for inflation, Gone with the Wind in the highest grossing Oscar winning movie.-If you mean the highest grossing movie that won the Best Picture Oscar, that would also be Gone with the Windunadjusted for inflation. It made 199 million dollars.
Australia
Titanic
The highest grossing Australian movie is Crocodile Dundee, with box office grosses over $47 million in 1986.
Most popular: Horror Highest Grossing: adults
The Lion King :)
Harry Potter
By highest selling, I assume you mean highest grossing. Highest Grossing Movie in the U.S.A (not adjusted for inflation): Titanic (1997) -- $600,779,824 (not adjusted) or $908,688,900 (adjusted) Highest Grossing Movie in the U.S.A (adjusted for inflation): Gone with the Wind -- $198,676,459 (not adjusted) or $1,430,476,000 (adjusted)