Heard joke once: Man goes to doctor. Says he's depressed. Says life seems harsh and cruel. Says he feels all alone in a threatening world where what lies ahead is vague and uncertain. Doctor says, "Treatment is simple. Great clown Pagliacci is in town tonight. Go and see him. That should pick you up." Man bursts into tears. Says, "But doctor…I am Pagliacci."

- Alan Moore, "Watchmen"

It is extremely disheartening to know that a man who brought so many smiles to people was himself a victim of severe depression. It is often said that the greatest comedy arises as a mechanism to alleviate pain. From what we now know, this appears to be the case for Robin Williams. A purveyor of joy for millions of people and a source of inspiration for his peers, Williams will always be remembered as one of the most brilliant comedic minds to have ever lived.

Although the late Robin Williams was most renowned for his comedic genius, he will also go down in history as one of the most versatile actors of his generation. Williams possessed the extraordinary capacity to entertain viewers of all ages. He had the ability to make us all laugh with his flair for humor and razor sharp wit, and every now and then, he would deliver outstanding performances in dramatic and serious roles. Just as Bryan Cranston proved with his captivating performance as drug kingpin Walter White in "Breaking Bad", some of the most heartfelt dramatic performances are often given by otherwise comedic actors.  In no particular order, following are 7 of the best performances delivered by Robin Williams, the actor.

1. "Dead Poets Society"

Arguably one of the most memorable and iconic of Williams' on-screen performances was as the inspirational English teacher John Keating in the 1989 film "Dead Poets Society." Directed by Australian director Peter Weir, the film is set in Welton Academy, an elite and orthodox prep school in the northeast United States in 1959. The narrative of the film revolves around the interactions between a group of seniors at Welton and their unconventional and charismatic new English teacher, Keating, who not only instills in them a passion for poetry, but also inculcates in them a countercultural ethos. He also imparts to his students a spirit to conquer the present moment through his motto, "carpe diem", which is latin for "seize the day."

2. "Good Will Hunting"

The role of psychologist Sean Maguire in Gus Van Sant's "Good Will Hunting (1997)" earned Williams an Academy Award for Best Supporting Actor. The film, written by Matt Damon and Ben Affleck, tells the story of Will Hunting, an immensely gifted janitor at M.I.T., played by Damon himself. Williams acts as counselor to this troubled genius and endeavors to help him reach his full potential. In this role, he showcases the subdued side of his acting, with a touching performance as a supportive and  compassionate mentor. "You can do anything you want, you are bound by nothing", his character famously says in the film.

3. "Mrs. Doubtfire"

At the forefront of his comedic roles is the dual performance as Daniel Hillard and Mrs. Doubtfire in the 1993 family comedy "Mrs. Doubtfire." In this Tootsie-inspired classic, Williams plays the role of a divorced family man who loves his children dearly but loses custody of them to his ex-wife. In an effort to reunite with his kids, Daniel assumes the disguise of a Scottish housekeeper named Mrs. Iphegenia Doubtfire, and hilarity ensues. Williams essays the role with masterful command, as this laugh-out-loud comedy often delves into touching instances where Daniel gradually realizes the nuances of good parenting.

4. "Aladdin"

In this animated feature film, Williams assumes the role of Genie, the witty and hilarious mystical cohort of "Aladdin." "Aladdin" follows the story of a street urchin who falls in love with a princess and vows to marry her. Trapped in a magic lamp, Genie is Aladdin's magical partner who grants him three wishes in order to help him woo the princess. Easily one of the most unforgettable characters of the film, Genie's amusing gags and hysterical antics stole the spotlight. The role was game-changing for the animated film industry as it was one of the first instances where an established Hollywood actor lent their voice to an animated offering, setting a trend of sorts.

5. "Insomnia"

Williams gave one of his most restrained performances in Christopher Nolan's 2002 suspense thriller "Insomnia." In the film, he portrays the character of twisted crime writer Walter Finch. Of the role, David Edelstein of New York Magazine wrote, "The key is what [Williams] doesn't do: Those rubber features remain rigid, that madcap energy harnessed. The sour little curl of Williams's mouth reminds me of Laurence Olivier in 'The Entertainer' - all the paranoid alertness of a stand-up comic with none of the genial pandering. There is nothing so despairing - or potentially so lethal - as a clown who has given up hope of making us laugh but wants to have an impact on us anyway."

6. "Good Morning, Vietnam"

In this cinematic gem from 1987, Williams plays the role of an amiable but irreverent DJ, Adrian Cronauer, who is assigned to the US Armed Services Radio station in Vietnam. Cronauer starts his broadcasts with an energetic, "Gooooood morning, Vietnaaaaam" and steals the hearts of a majority of the troops with his dynamic personality and his heretical ramblings about the truth of the war. However, as a result of going against the official government stance over the war, he loses his job and gets replaced. Williams acts as a charming ray of hope through this part, in the midst of hopelessness and misery.

7. "The Fisher King"

Robin Williams and director Terry Gilliam are a match made in heaven. Through their work, they both occupy a thin line between comedy and seriousness. In this adaptation of Richard LaGravenese's mythical tale of redemption set in New York City, Williams plays an eccentric homeless man named Parry, who is driven to insanity by the death of his wife. Parry frantically oscillates between farce and melancholy, as he seeks the assistance of radio DJ Jack Lucas (played by Jeff Bridges) to save his soul. In order to achieve this, the unlikely duo set out on an adventure to find the Holy Grail. Williams delivers an exceptional performance as a funny man with deep-rooted darkness.

Reach Staff Reporter Adi Radia here and follow him on Twitter here.