The Oscar-nominated actor died in 2008, aged 28, after accidentally overdosing on a cocktail of prescription painkillers, anti-anxiety drugs and sleeping pills, according to New York authorities.
Ledger was best known for his roles in Brokeback Mountain and The Dark Knight.
An empty bottle of sleeping pills was reportedly by the icon's side when she was found dead in her hotel room in August, 1962, but speculation over the true cause of her death continues. Some believe she committed suicide, some think she accidentally overdosed on prescription pills, and others suggest third-party involvement.
A lethal combination of pneumonia, anaemia and prescription drugs caused the Clueless star's death in December 2009, according to the Los Angeles coroner. Investigators reportedly found more than 10 different types of pills on the 32-year-old's bedside table, including treatments for migraines and depression.
Anna Nicole Smith
A six-week investigation came to the conclusion that the former Playboy model had not committed suicide in her Florida hotel room in 2007, but had died after taking nine prescription drugs. Authorities said each drug was present in her bloodstream in small amounts, but it was their combined effect which had proven deadly.
Plenty of conspiracy theories abound over the death of the King, one of which includes the suggestion that a titanic appetite for prescription drugs may have killed him. George Nichopoulos (who spent a decade as Elvis's personal physician before his medical licence was revoked) has admitted prescribing around 10,000 doses of drugs (including laxatives and hormones) for Elvis in 1977 alone -- the year that the singer died in August in his Memphis mansion at the age of 42.