Sean Penn, arguably one of the greatest actors of our time, is the epitome of a chameleon. Having taken us from the depths of human despair in Dead Man Walking to a revolutionary figure in Milk, this is a man with some serious acting chops, and he has two Oscars to prove it. Yet, with plenty more strings to his bow, including director, screenwriter, and humanitarian, he is just as much a force to be reckoned with off-screen as he is on-screen.

While his most recent acting and directorial offering, Flag Day, has received mixed reviews, the bulk of the actor’s back catalog is truly something to marvel at. Here are just a few performances that showcase his versatility and depth, making him one of the top dogs of Hollywood.

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Matthew Poncelet in Dead Man Walking (1995)

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Image via Gramercy Pictures

Although Penn had been on the scene for a couple of decades beforehand, Dead Man Walking was the film that catapulted him to the Hollywood A-list. He was Oscar nominated for the role of Matthew Poncelet, a death-row inmate who develops a special relationship with the nun, Sister Helen Prejean (Susan Sarandon), who visits him.

Adapted from the real-life Sister Helen’s memoir of the same name, this film is a powerful and emotional look at a controversial issue in society and definitely calls for a stellar cast. Cue Mr. Penn. In this role, Penn takes a character convicted of murder and rape and shows his humanity. Poncelet is, at first glance, the type you would want to stay away from. With his tough, tattooed clad appearance and intimidating stare, he fits the jailbird stereotype. Yet, after several meetings with Sister Helen, we get to see a human being searching for spiritual guidance. Penn manages to perfectly balance the blend of light and dark in a person in this riveting role.

Sam Dawson in I Am Sam (2001)

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Image via New Line Cinema

Is there anything more heartbreaking for an actor to portray than a parent fighting for custody of a child? Perhaps a mentally challenged parent fighting for custody of a child? Well, this was Penn’s task with the moving drama, I Am Sam. Although many critics were keen to point out the flaws, this film is a thought-provoking look at how society treats people deemed to be “different” and Penn’s performance in the title role of Sam is nothing short of spectacular. The actor’s keen eye for even the smallest of details, such as a tick or a subtle look takes the character to another level. We see a kind-hearted single parent with so much love for his young daughter, Lucy (Dakota Fanning), but due to the hand he was dealt at birth, he has to fight for his right to take care of her. The scenes between Penn and the young Fanning are like watching an acting masterclass, but be warned you may want to have some tissues at the ready.

Jimmy Markum in Mystic River (2003)

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Image via Warner Bros.

It’s hard to believe that despite being in the business since the 70s, it wasn’t until 2004 that Penn finally got his hands on the Oscar. But for his performance in Mystic River, it was worth the wait. Adapted from Dennis Lehane’s novel of the same name, Mystic River tells the story of three men with a haunting past whose lives intertwine decades later in connection with a murder investigation.

Although this film is a powerhouse of talent, with the likes of Tim Robbins and Kevin Bacon in supporting roles and Clint Eastwood in the director’s chair, Penn’s performance still manages to give it that extra intensity. Playing the leading role of Jimmy, an ex-con whose daughter has just been murdered, Penn once again delves into a character full of layers and complexities and has that rare ability to make you root for and against him all in the same scene.

Harvey Milk in Milk (2008)

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Image via Focus Features

Milk proves that Penn can not only perfect fictional characters but can also be an expert impersonator. Harvey Milk, one of the first openly gay elected officials in the U.S., was an enthusiastic activist, and Penn pins down his every gesture to a T. With Penn not shy about expressing his own political views off-screen, this natural persona was able to shine through on-screen. From the gripping motivational speech scenes to the intimate moments between Milk and his lovers, Penn brings his A-game to the role, allowing you to see all the sides of this influential politician. This performance is a true testament to Penn’s ability to fully embody every character he takes on, both real and fictional.

Samuel Byck in The Assassination of Richard Nixon (2004)

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Image via ThinkFilm

While many of Penn’s characters may look similar on paper, often carrying some sort of inner turmoil, it is the actor’s impeccable range of characteristics, voice work, and quirks that makes every character unique. In The Assassination of Richard Nixon, Penn nails the array of emotions needed to understand a person capable of potentially committing an atrocious act.

This film tells the true story of an obscure incident in which a disillusioned failed salesman, Samuel Byck (portrayed by Penn), plans to hijack a plane, crash it into the White House and ultimately assassinate the president. What Penn pulls off so magically though is the unspoken rage inside Byck’s head, something only actors worth their salt could manage. With just a facial expression or nervous movement, we know this man is a pressure cooker ready to explode. Perhaps it’s Penn’s own directorial and writing experience which allow him to understand the importance of even the tiniest details.

Jeff Spicoli in Fast Times at Ridgemont High (1982)

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Image via Universal

Sporting long wavy blond locks and a surfer dude drawl, Penn gives a memorable performance as Jeff Spicoli in his breakout role. Amy Heckerling’s directorial debut, Fast Times at Ridgemont High is the American Pie of the ‘80s. It follows a group of high schoolers throughout a school year as they delve into the world of sex, drugs, and rock n’ roll.

Although Penn wasn’t going to win any Oscars with this one, he proves that he is just as comfortable in comedy as he is in hard-hitting dramas. Little did we know what was to come from the actor that gave us this portrayal of dim-witted stoner Spicoli, but it certainly shows that his acting range has no bounds.

David Kleinfeld in Carlito’s Way (1993)

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Image via Universal Pictures

Taking on a supporting role alongside the legend that is Al Pacino, Penn is almost unrecognizable in this part. He plays mob boss Carlito Brigante’s (Pacino) sleazy lawyer, David Kleinfeld, who ends up getting in way over his head with gangster dealings.

Penn’s performance as the erratic, coked-up lawyer, with an unforgettable permed hairdo earned him a Golden Globe nomination, as well as some serious credit for almost outshining Mr. Pacino himself. And the chemistry between the two heavyweight actors is something that begs a rewatch.

Cheyenne in This Must Be the Place (2011)

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Image via Element Pictures

This Must Be the Place tells the story of a former rock star, Cheyenne (Penn), who sets out on a road trip to seek revenge for the torture his recently deceased father faced in World War II at the hands of a Nazi guard. Paolo Sorrentino’s drama sees the actor once again transform himself beyond recognition. Disguised in goth makeup, a prominent black wig, and putting on a high-pitched voice, Penn portrays the character of Cheyenne with incredible precision and heart. It seems a 50-year-old jaded rock star clinging to his youth is yet another persona Penn was born to play. A touching story of life, death, loss, and all things in between, it is an important addition to the actor’s expansive filmography.

Jim in We’re No Angels (1989)

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Image via Paramount Pictures

A young Penn and Robert De Niro playing two escaped convicts trying to pass themselves off as priests, does it get any better than that? A remake of the 1955 movie of the same, We’re No Angels is a comedy that displays Penn’s remarkable charisma. The premise alone offers up a fair few opportunities for hilarious hijinks, such as when Penn’s character, Jim, gets called upon to perform mass, however, it’s Penn’s impeccable comedic timing and excellent use of facial expressions that make the movie work so well. Of course, having De Niro and Demi Moore as co-stars doesn’t hurt either.