For the best part of a decade he was Hollywood’s most notorious cautionary tale.

After being tipped for stardom, Robert Downey Jr spent the late 1990s and early 2000s addicted to drugs and reduced to earning eight cents an hour scrubbing pizza pans in the kitchen of the LA County jail during regular stints in prison.

So it is all the more remarkable that the 50-year-old was yesterday named the best-paid male actor for the third year running, raking in £51million.

Just how did he achieve this remarkable change of fortunes? Fittingly a superhero transformation is behind his success.

Forbes, which compiled the list, said Downey Jr has managed to earn the ‘stratospheric’ amount thanks to his starring role in the Iron Man films, what has become the biggest movie franchise in the world.

He was first cast as eccentric billionaire inventor Tony Stark, who transforms into Iron Man, seven years ago, alongside Gwyneth Paltrow, who plays his love interest, Pepper Potts.

Since then he has starred in four more films. Avengers: Age of Ultron, the most recent instalment, has pulled in a massive £830million worldwide since its release earlier this year.

These days there are remarkable parallels between the actor and his on-screen alter-ego.

Like Stark, Downey Jr lives in Malibu, but in an eccentrically decorated £10million ranch with its own gym, rose-covered stabling for 12 horses and riding rings. He also owns a £5million pad in the trendy LA neighbourhood of Venice Beach.

The luxury doesn’t stop there. He travels by private jet, has his own chef and indulges eccentricities in true Hollywood diva fashion, taking his furniture with him when he films on location.

Yet it was not that many years ago that it looked like he would lose his life to substance abuse.

The star reportedly had his first experience of drugs when he was only six years old after his father, a drug-addict underground film maker, Robert Downey, let him try a cannabis joint.

The actor claims he started taking drugs with his father as an emotional bonding experience. He recalls he was soon getting drunk every night and ‘making a thousand phone calls in pursuit of drugs’.

Dropping out of school early to study acting, he was spotted playing a drug-addled rich kid in the 1987 cult film Less Than Zero.

As his profile grew, he had flings with a string of Hollywood actresses including Marisa Tomei, and had a much longer relationship with Sarah Jessica Parker, years before she became famous in Sex And The City.

After being tipped for stardom, Robert Downey Jr spent the late 1990s and early 2000s addicted to drugs and reduced to earning eight cents an hour scrubbing pizza pans in the kitchen of the LA County jail during regular stints in prison (pictured in court in 1999)

In 2001, he was arrested for being under the influence of a controlled substance (police photo, left). It followed a courtroom appearance in 1997 where he was  jailed for violating parole (right)

He once told a judge that taking drugs was ‘like having a shotgun in my mouth with my finger on the trigger, and I like the taste of gun metal’ (pictured in court in 2001 for drugs charges)

His starring role in Sir Richard Attenborough’s 1992 biopic Chaplin should have propelled him into the film industry’s hall of fame.

He was routinely described – not least by himself – as the greatest actor of his generation, bringing an unmatched intensity and versatility to the screen.

Instead, drug abuse dragged him to the bottom.

His first marriage, to actress Deborah Falconer in 1992, produced a son, Indio, but Downey Jr’s repeated trips to jail and rehab for heroin and cocaine abuse destroyed the relationship.

On one occasion he was arrested, naked and hallucinating, at the wheel of his Porsche. Another time, he was discovered in a foetal position in a vermin-infested alley behind a squalid LA hotel.

He once told a judge that taking drugs was ‘like having a shotgun in my mouth with my finger on the trigger, and I like the taste of gun metal’. Guns and drugs were mutual obsessions. Downey Jr once turned up to meet the British director Mike Figgis two hours late, barefoot and carrying a loaded shotgun he couldn’t explain.

In April 1996, he was arrested for possession of heroin, cocaine and a .357 Magnum handgun – this one unloaded – while roaring down Hollywood’s Sunset Boulevard.

Despite his ups and downs, the actor has gone onto become the highest paid in Hollywood – beating the likes of Tom Cruise and Johnny Depp

His success is down to his titular role in the smash box office Iron Man – which spawned four more films

His starring role in Sir Richard Attenborough’s 1992 biopic Chaplin could have propelled him into the film industry’s hall of fame if not for the drugs but the Marvel franchise returned him to the A-list

In 1997, after missing repeated drugs tests, he was given a 180-day jail sentence for violating probation but was caught fighting with another inmate. Fellow prisoners reportedly targeted the celebrity in their midst and Downey Jr twice woke up in a pool of his own blood.

‘I would never tell you the worst things that have happened to me,’ he once said of his time behind bars.

The actor spent another year incarcerated, this time undergoing drug treatment, in 1999. A week after his release he joined the cast of the TV series Ally McBeal as the new love interest of its main character, played by Calista Flockhart. But the job didn’t last.

In 2001, he was sacked from the series following another drugs arrest in which he had been found wandering the streets, barefoot and high on drugs. His long-suffering wife followed the example of Sarah Jessica Parker and left him, taking their son with him.

He was by now a pariah in Hollywood and, pursued over unpaid taxes, he almost went bankrupt.

Then, in 2003, he met his current wife, producer Susan Levin. Downey Jr credits her with his remarkable turnaround as she insisted she would never marry him unless he gave up drugs for good.

In 2003, he met his current wife, producer Susan Levin. Downey Jr credits her with his remarkable turnaround as she insisted she would never marry him unless he gave up drugs for good

Downey Jr also starred as Sherlock Holmes across from Jude Law in another popular franchise

In suitably dramatic fashion, he stopped outside a roadside Burger King and threw all his drugs into the Pacific Ocean. He entered a 12-step programme to tackle his addictions, took up meditation and describes beating his addictions as coming out of a ‘20-year coma’. Downey Jr insists he hasn’t touched powerful stimulants ever since.

His career started to recover within months of his pledge to give up drugs and he is now apparently a devoted family man, taking Susan and their young son Exton and daughter Avri with him as travels the globe.

Downey Jr’s £51million earnings are considerably higher than the actor ranked second, Hong Kong-born martial arts star Jackie Chan, who pulled in £32million from his action films. In third place was Vin Diesel who earned £30million thanks to the success of the Fast and The Furious franchise.

Bradley Cooper, who is currently starring on the London stage in Elephant Man, was fourth with a £26million haul from roles in films such as American Sniper, while comedian Adam Sandler was in fifth with £25million.

Rounding out the top ten were Tom Cruise in sixth on £24million, Bollywood stars Amitabh Bachchan and Salman Khan rank at joint seventh with £21million and Akshay Kumar was ninth on £20.8million.