Heath Ledger's disturbing final diary entry gives sad insight into his mentality

Some of the final diary entries written by Heath Ledger have revealed the somewhat harrowing dedication the actor made to his final movie role.

The Dark Night star tragically passed away back in 2008 following an accidental prescription drug overdose, just months after he first opened up to press about his ongoing mental health issues.

This week, almost two decades on from his tragic death, the final entry Heath made in the journal he kept while filming the award-winning The Dark Knight has been doing the rounds on social media, giving fans an insight into his headspace at the time while getting into character.

When Heath was cast as notorious killer clown in 2006, the Australian actor received mass backlash from a number of industry professionals - as well as fans of the DC comic franchise - who considered him inappropriate for the role.

Despite being ceaseless compared to those who'd maintained the villainous role before him - particularly Hollywood legend Jack Nicolson - he refused to let down director Christopher Nolan.

Heath won several accolades for his portrayal of the DC Comics villain. (Warnes Bros/IMDB)

So much so, that while preparing to film the franchise's second instalment, Heath locked himself in a hotel room for over a month in the hope of understanding the mindset of the - as he called him - 'psychopathic, mass-murdering, schizophrenic clown' he'd soon be playing.

The father-of-one - who'd previously appeared in blockbuster hits including Brokeback Mountain and 10 Things I Hate About You - also kept a 'Joker' diary at this time.

According to his friends and family, this written and visual work contained often sadistic items which he believed would resonate with his sinister character, including jokes about murdered animals and AIDS.

Heath kept a diary while preparing for the role of 'Joker'. (Broadview Pictures)

Ever since his death aged 28, images from said diary have sporadically began circulating on social media, with one harrowing page in particular leaving fans in shock.

Among the cruel jokes, heinous comments and bizarre pictures later found inside the diary were the chilling words 'BYE BYE', which the actor had seemingly scrawled across his journal's back page.

Speaking of the diary in the years after his son's death, the actor's father Kim told press: "He galvanised the upcoming character. That was typical of Heath. He would do that.

The entries were shown during a documentary on his life (Broadview Pictures)

His final entry (Broadview Pictures)

"He liked to dive into his characters, but this time he really took it up a notch. He immersed himself in the upcoming character on every level."

Prior to his death, Heath battled both substance abuse issues, as well as raging insomnia.

And tragically, seven months prior to the release of the movie he'd spent over two years preparing and filming for - for which he was posthumously awarded Best Actor awards at the 2008 Oscars, BAFTAS and Golden Globes - Heath was found unresponsive in his Manhattan home.

Despite paramedics performing CPR on the star for several minutes, he was pronounced dead at 3.36pm on 22 January 2008.