Johnny Be Good (1988)
The Film: Downey’s on best friend duties in one of his earlier film roles, playing the geeky compadre to Anthony Michael Hall’s jockstrap-wearing football-lover.
Delightful Downey: Hall’s stretching the boundaries of plausibility playing a jock so soon after geeking up the likes of Sixteen Candles and Weird Science , but it’s Downey who makes this watchable. He’s naturally funny, pulling off an off-beat likability.
Danger Zone (1996)
The Film: Sporting a truly awful haircut, Downey Jr’s a one man army attempting to rescue this forgettable action flick – which also stars Billy Zane – from its own awfulness. The plot revolves around an African civil war.
Delightful Downey: Championing a Southern drawl, Downey Jr’s good for entertainment value. The reason he signed up? “Five hundred grand for two weeks.” Aha.
The Singing Detective (2003)
The Film: Novelist Dan Dark (Downey Jr) slips into feverish dreams as he suffers from various skin diseases. Rolling around in his dreams, he finds himself living out an unconscious film noir, which follows the plot of one of his novels, and re-examining his disturbing childhood.
Delightful Downey: You can see Downey Jr just willing this to work, and he puts in 101% effort. Sadly, even he can’t lift this woeful musical out of the bargain bin at Blockbusters.
The Film: People repeatedly tell Halle Berry she’s crazy in this dreadful ghost flick, but the same could be said of Downey Jr himself – why did he even sign up to it? “I decided I’d do it before I read it,” Downey admits, before revealing he was lured into the film by his rather gorgeous co-star. D’oh.
Delightful Downey: Being the only sane one in a madhouse must be hell (just ask Berry’s character), but Downey Jr pulls off a remarkably put-together performance in a film that’s hysterical in all the wrong ways.
Two Girls And A Guy (1997)
The Film: Not to be mixed up with the Ryan Reynolds TV series Two Guys And A Girl . This low ebb com-dram has Downey playing Blake Allen, a narcissistic actor who’s stringing along Heather Graham and Natasha Gregson Wagner.
Delightful Downey: The film itself is pretty dim-witted, but its single location (Allen’s apartment) and emphasis on dialogue is what Downey Jr was born for.
Here, he rattles off some killer improvised lines, proving he really is the best thing about it. “I knew [ director James ] Toback would give me the freedom to let my spirit go,” he says.
The Film: Bubbly backstage comedy that follows the behind-the-scenes shenanigans of a daytime soap opera. Producer David Seton Barnes (Downey Jr) schemes with the gorgeous Montana Moorehead (Cathy Moriarty) to supplant the intolerable Celeste Talbert (Sally Field) from her position as star of the show. Get that?
Delightful Downey: “If she doesn't speak, we don’t have to pay her as much. A homeless deaf mute. What could be more pathetic? God, I’m good.”
Donning some nifty specs and bedroom eyes, Downey Jr is smarmy but loveably so. He also gets most of the best lines, though his suggestion that Barnes have a urine fetish was vetoed by the director.
US Marshals (1998)
The Film: Downey Jr calls it “possibly the worst action movie of all time”, but it’s worth it for his performance as an untrustworthy special agent, whom Samuel Gerard (Tommy Lee Jones) comes across as he attempts to re-capture a runaway Wesley Snipes.
Delightful Downey: Revelling in the gunplay, Downey Jr’s cool as ice here. So what if he thought it was dumb? When you get to run around with a grizzled Tommy Lee Jones all day (and get paid for it), things can’t be all that bad.
"I don't remember anything about U.S. Marshals except that we were running around and pretending like we could ever hold a candle to The Fugitive ," the actor recalls.
Weird Science (1985)
The Film: Cult classic in which two nerds use their science know-how to create the perfect woman – who just so happens to look like model Kelly LeBrock. Downey Jr plays Ian, a high school bully who makes the nerds’ lives a misery.
Delightful Downey: As bully Ian, he’s basically only there to get trampled on when the geeks get the girl, but Downey Jr’s down with that.
"At that time, walking into a production office on the Universal lot and seeing Anthony Michael Hall was like bumping into Spencer Tracy at the commissary in the 1940s," remembers the actor. "If John Hughes hadn't put me in Weird Science , who knows what would have happened?"
Tropic Thunder (2008)
The Film: Action movie send up in which Downey Jr plays Australian method actor Lazarus, who just so happens to be black. When a group of actors attempt to make a Vietnam war film, they find themselves caught up in the middle of a real war - and decide to go Method.
Delightful Downey: So good he got an Oscar nomination. Not just any actor would agree to darken their skin as the walking punchline of a resolutely silly action flick. But then, Downey Jr isn’t just any actor.
Here, he's daring and hysterical. And, apparently, he based the character on Terrence Howard, who he’d just worked with on Iron Man .
Sherlock Holmes: A Game Of Shadows (2011)
The Film: Better than its predecessor in just about every way, Game Of Shadows is a spirited sequel that has Downey Jr on fine form as the eponymous investigator. This time, he’s up against the villainous Moriarty (Jared Harris), with trusty old Watson (Jude Law) still at his side.
Delightful Downey: Dressing up as a woman, outrunning bullets and, in one segment, even dying, Downey Jr plays Holmes with palpable glee.
“This Some Like It Hot moment was kind of my idea,” he reveals, proving he’s game for as much homoeroticism as the audience demands.
Short Cuts (1993)
The Film: Based on short stories by Raymond Carver, director Robert Altman explores American society through the eyes of variously disconnected individuals. Amid the intertwining storylines we find Downey Jr playing Bill Bush, a womanising special effects artist.
Delightful Downey: Swigging beer and turning the charm dial up to 11, Downey’s a sleazy, sloppy delight here.
Sure, he’s up against the likes of Julianne Moore (in the buff) and Jack Lemmon, but the actor’s grungy magnetism ensures he stands out from the crowd.
The Film: A biographical exploration of the life of cinema’s most famous silent movie star, Charlie Chaplin. Chaplin (Downey Jr) looks back over his life, recalling the poverty of his early years and his love for London music halls.
Delightful Downey: Quite simply a tour de force. Emulating Chaplin perfectly, Downey Jr disappears under the period costume and the signature moustache, damn near becoming the silent movie star before our very eyes.
He deserved that Oscar nod. And then some.
Kiss Kiss Bang Bang (2005)
The Film: A neo-noir masterpiece written and directed by Shane Black ( Lethal Weapon ). Downey Jr plays petty criminal Harry Lockhart, who becomes an actor after stumbling into an audition while he’s on the run from the cops.
Delightful Downey: Dishevelled, sarcastic and really, really funny, Downey Jr proved he still had leading man prowess after a string of duds in the early Noughties.
Sparking a fantastic rapport with Val Kilmer, Downey Jr nails Shane Black’s tongue-twisty dialogue. We can’t wait to see these guys back together for Iron Man 3 .
The Film: Dark, ambient thriller, in which the murder mystery isn’t quite as fascinating as the men in charge of the investigation. San Francisco Chronicle writer Paul Avery (Robert Downey Jr) receives a letter from the so-called Zodiac Killer and attempts to unravel the mystery surrounding him.
Delightful Downey: Tucking away his smart tongue and reigning in his love for the flamboyant, Downey Jr is admirably measured and restrained in David Fincher’s epic drama.
Later, Downey Jr joked that Fincher insisted on “75 takes of picking up a fucking telephone”. He obviously relished the challenge.
Avengers Assemble (2012)
The Film: No Iron Man on this list? Well, with Avengers Assemble , it’s sort of a moot point. Downey Jr reprises his role as Tony Stark, becoming one of The Avengers – alongside Thor, Captain America, Hulk, Black Widow and Hawkeye – who must stop evil god Loki from taking over Earth.
Delightful Downey: Scattershot hilarious in Iron Man 1 and 2 , Downey Jr’s even better with Joss Whedon putting words in his mouth.
Slinking catlike through every scene, he shares screwball pizzazz with Gwyneth Paltrow, spits insults at Fury and Hulk, and nicknames Captain America ‘capcicle’. Downey Jr, we love you.