Tom Hanks - "Philadelphia" (1993)   

Tom Hanks lost 26 pounds for his Oscar-winning turn as AIDS patient Andrew Beckett in "Philadelphia." 

Also Read: Tom Hanks to Play Captain Sully Sullenberger in Clint Eastwood Drama

Matt Damon - "Courage Under Fire" (1996)   

Matt Damon reportedly lost 40 pounds for his role as a soldier in "Courage Under Fire" opposite Denzel Washington. 

Also Read: Matt Damon Mocks Fellow Astronauts in ‘The Martian’ Deleted Scene (Video)

Tom Hanks - "Cast Away" (2000)   

Hanks again took it down a few (belt) notches in "Cast Away." 

Also Read: Tom Hanks Reunites With Wilson From ‘Cast Away’ 15 Years Later (Video)

Christian Bale - "The Machinist" (2004)   

Christian Bale became frighteningly thin for "The Machinist," dropping 60 pounds. This would not be the only time he would put his body through an extreme transformation, going to similar lengths for his part in "The Fighter" and "Rescue Dawn." 

Also Read: AFI FEST Party Pictures: Ryan Gosling, Christian Bale, Will Smith, Brad Pitt, Angelina Jolie Shine in Hollywood (Updating Photos)

Beyoncé - "Dreamgirls" (2006)   

Beyoncé dropped 20 pounds from her "Bootylicious" body with the help of a cleanse for her role in "Dreamgirls." 

Also Read: Beyonce Pulls Biggest Power Play Yet: No Interview for Vogue Cover Story

Michael Fassbender - "Hunger" (2008) 

Michael Fassbender dropped an alarming amount of weight to play IRA hunger striker Bobby Sands in "Hunger." 

Mila Kunis - "Black Swan" (2010)   

Mila Kunis slimmed down by 20 pounds for the ballet thriller "Black Swan." 

Also Read: ‘Black Swan’ Reviewed: Just a Little Tutu Crazy Ballet Tale

Natalie Portman - "Black Swan" (2010)   

So did Kunis' Oscar-winning "Black Swan" co-star Natalie Portman. 

Also Read: Paris Attacks: Steven Spielberg, Natalie Portman French Movie Premieres Canceled

Seth Rogen - "The Green Hornet" (2011)   

Seth Rogen slimmed down considerably for "The Green Hornet." Unfortunately, the audience for that movie was also small. 

50 Cent - "All Things Fall Apart" (2011)   

50 Cent looked more like a thin dime after dropping 50-plus pounds to play a football player with cancer in the indie drama "All Things Fall Apart." 

Also Read: 50 Cent Testifies That His Flashy Lifestyle Is an Illusion

Anne Hathaway - "Les Miserables" (2012)   

Anne Hathaway opened up her mouth to sing -- but apparently not to eat much -- for "Les Miserables," shedding around 25 pounds (not to mention a whole lot of hair in one harrowing scene) for the Oscar-winning role. 

Also Read: ‘Les Misérables’ Footage of Anne Hathaway Singing ‘I Dreamed a Dream’ Screens at CinemaCon

Matthew McConaughey - "Dallas Buyers Club" (2013)   

Matthew McConaughey upped his profile and won practically every possible acting award -- including an Oscar -- after dropping nearly 40 pounds to play a Texan with AIDS for the "Dallas Buyers Club." 

Also Read: Matthew McConaughey on ‘Dallas Buyers Club’ Weight Loss, Tracking Wolves With Young Son (Videos)

Jared Leto - "Dallas Buyers Club" (2013)    

McConaughey's co-star Jared Leto was no slouch in the weight-loss department either, shedding 30 to 40 pounds and picking up his own Oscar in the process. 

Also Read: Jared Leto, Celine Dion Pay Emotional Tribute to Paris at AMAs (Video)

Zoe Kravitz - "The Road Within" (2014)    

Zoe Kravitz weighed just 90 pounds at the time of filming for "The Road Within," having lost 20 pounds for the part. But she revealed that like her character in that movie, she too had struggled with anorexia in her real life. 

Also Read: 65 Stars Who Have Condemned Harvey Weinstein (Photos)

Chris Hemsworth - "In the Heart of the Sea" (2015)   

Chris Hemsworth shocked the internet when the "Thor" hunk revealed the dramatic weight loss he endured to play a shipwreck survivor in the fact-based period drama.

Also Read: Chris Hemsworth Shares Shocking Photo of Extreme Weight Loss for ‘In The Heart of the Sea’

Liam Neeson - "Silence" (2016)   

Liam Neeson shed some serious weight for Martin Scorsese's historical drama "Silence." Then 65, Neeson at one point said he took his weight loss "too far" in service of the part. 

Also Read: Liam Neeson on ’60 Minutes': Why The ‘Non-Stop’ Star Makes All Those Action Movies (Video)

Lily Collins - "To the Bone" (2017)   

Lily Collins had struggled with anorexia and bulimia in her own life, but she said that losing weight to play a woman suffering from anorexia was important to do justice to the role. She then worked closely with nutritionists to ensure she actually gained the weight back. 

Taylor Kitsch - "Waco" (2018)  

Taylor Kitsch revealed on the "Ellen DeGeneres Show" that he lost 30 pounds to play cult leader David Koresh in Paramount Network's limited series "Waco." “I’d get 500 calories at breakfast and then it would go from like veggies in the mid-afternoon to chicken broth after 4 o’ clock. And then you go run, which is awesome!” he said. 

Joaquin Phoenix - "Joker" (2019) 

The actor lost 52 pounds to play the role of Arthur Fleck, the troubled and deranged comedian who becomes the iconic Batman villain Joker. This was shortly after Phoenix beefed up to play a hitman in Lynne Ramsay's "You Were Never Really Here." "Joker" director Todd Phillips told Vanity Fair that the actor resembled a bird from the Gulf of Mexico having tar rinsed off its body.