Horror fans are celebrating the 40th anniversary of the genre favorite An American Werewolf in London. Written and directed by John Landis, the movie premiered on the big screen on Aug. 21, 1981, to great success at the box office. It was also a hit with critics and won the Saturn Award for Best Horror Film that year. Over the past four decades, the cult classic is still highly revered and widely considered to be one of the greatest werewolf movies ever made.

The synopsis for the movie reads: "David (David Naughton) and Jack (Griffin Dunne), two American college students, are backpacking through Britain when a large wolf attacks them. David survives with a bite, but Jack is brutally killed. As David heals in the hospital, he's plagued by violent nightmares of his mutilated friend, who warns David that he is becoming a werewolf. When David discovers the horrible truth, he contemplates committing suicide before the next full moon causes him to transform from man to murderous beast."

In honor of An American Werewolf in London's 25th anniversary in 2006, Naughton told SF Site, "The story was very much there and intact in the script and that's what we shot -- which I thought was a fairly straight forward tragic love story. Tragic in a sense that here are these characters that don't really have any control over what happens to them. And then there's the idea that the two buddies -- one of whom is killed on the moors -- continue to have scenes together, which I thought was very funny and unique. But it reads as a straight forward story where a guy can't believe what his friend is telling him, and he falls in love with a nurse and ultimately succumbs to the tragedy of being a werewolf."

In particular, Rick Baker's work on the makeup for An American Werewolf in London has especially earned the movie great praise. His work even earned the movie the first ever Academy Award for Best Makeup, setting the stage for what practical effects could do for horror movies heading into the 1980s. In a 2011 interview looking back on the movie, Baker explained the inspiration behind the legendary werewolf transformation scene.

"[Landis] told me what he wanted the transformation to be," Baker said at the time, via Birth Movies Death. "We both loved seeing Fredric March turn into Mr. Hyde and Lon Chaney Jr. turn into the wolf man. But it just doesn't make sense for them to sit still and change a little bit, and then change and change, and then get up and move. He thought that transformation would be painful and he wanted to show the pain."

Based on the success of the original, the movie was later followed by a sequel. Called An American Werewolf in Paris, the followup was released in 1997 with an entirely different cast and crew, bearing little in resemblance to the first movie beyond its name and werewolf theme. More recently, there have been rumors of The Walking Dead creator developing a new reboot of An American Werewolf in London, but many fans of the original are leery of that idea after the sequel flopped.

After 40 years, it's clear that An American Werewolf in London will always have its place in cinematic history, regardless of any sequels or potential remakes. Happy 40th anniversary to a true horror classic. If you want to revisit the movie, it's streaming for free on Pluto TV.