BRAD PITT and ANGELINA JOLIE, Mr. and Mrs. Smith (2005)
The dueling megastars' white-hot chemistry onscreen apparently led to some offscreen sparks: by the time Mr. and Mrs. Smith hit theaters, Pitt was divorced from Jennifer Aniston and in a relationship with Jolie. The media-consuming controversy led to a global box office total of $478 million. —Darren Franich

TOM CRUISE and NICOLE KIDMAN, Eyes Wide Shut (1999)
An aura of profound secrecy hung over this marital drama for years before its release. The notion of Cruise and Kidman — at the time one of Hollywood's pre-eminent couples — working with the famously mysterious director Stanley Kubrick led to a fever pitch of anticipation. So it shouldn't have been a surprise that the finished product — a slow, meditative, and not very erotic (despite the orgy) peek into married life — proved to be a disappointment. Less expected: Two years later, Kidman and Cruise divorced. —DF

CARY GRANT and INGRID BERGMAN, Notorious (1946)
In Hitchcock's glittery post-war thriller, Bergman is the daughter of a Nazi spy, Grant is the secret agent who recruits her for an assignment in Brazil, and the romance that blossoms between them is dangerously sexy for the '40s. In one famous two-and-a-half-minute shot, Grant and Bergman share a long series of kisses — a sequence that almost didn't make it past the Production Code. —DF

MEL GIBSON and JODIE FOSTER, Maverick (1994)
Gibson and Foster made an adorably backstabbing pair in this comedy-western. The film was a box office success, and although the intervening years have (to say the least) soured the public on Mad Mel, Foster remains close friends with him, most recently casting him as her husband in her upcoming directorial effort The Beaver. —DF

BRAD PITT and JULIA ROBERTS, The Mexican (2001)
Sometimes when stars collide, sparks don't fly. Lisa Schwarzbaum gave the flick a C+, saying that while Brad and Julia entertained ''as movie stars can,'' they neglected to create characters worth caring about. But look how pretty they are! —Hillary Busis

RICHARD BURTON and ELIZABETH TAYLOR, Cleopatra (1963)
Critics savaged this epic, expensive flop — and audiences also stayed away in droves, scandalized when news broke of Taylor's off-screen romance with the married Burton. Their tumultuous relationship would go on to eclipse Cleopatra in the public eye. —HB

ELIZABETH TAYLOR and PAUL NEWMAN, Cat on a Hot Tin Roof (1958)
Critics agreed that these Hollywood heavyweights were evenly matched as Maggie the Cat and her depressed husband, Brick. Both Newman and Taylor scored Academy Award nominations for their performances, even though the movie was a much-sanitized version of the original Tennessee Williams play. —HB

ROBERT REDFORD and MERYL STREEP, Out of Africa (1985)
This Best Picture-winner garnered praise for Streep's intense performance as writer Karen Blixen, though Redford's portrayal of her aristocratic lover, Denys Finch Hatton, was less heralded. —HB

WARREN BEATTY and MADONNA, Dick Tracy (1990)
Given Beatty's playboy reputation, news that he was getting into the groove with the Material Girl came as no surprise. The romance carried over onto the screen with their performances in the color-coded live-action cartoon Dick Tracy, in which Madonna played the femme fatale to Beatty's yellow-coated detective. They had plenty of chemistry, that is, when their characters weren't trying to kill each other. —Keith Staskiewicz

CARY GRANT and KATHERINE HEPBURN, The Philadelphia Story (1940)
The classic George Cukor-directed screwball comedy married two great stars with two great voices — his mid-Atlantic accent with her distinctive Brahmin — and threw in James Stewart's iconic warble for good measure. Grant and Hepburn lit up the screen together, as they did previously in Holiday and Bringing Up Baby. —KS

HUMPHREY BOGART and LAUREN BACALL, The Big Sleep (1946)
One of cinema's great romances, both off-screen and on, Bogie and Bacall starred in four films together, but Howard Hawks' labyrinthine noir classic is quite possibly their greatest. —KS

JAMES STEWART and GRACE KELLY, Rear Window (1954)
Sure Grace Kelly could probably do better than a peeping-tom photographer in a leg cast — a prince, perhaps — but, then again, it is Jimmy Stewart. How can you not like him? Alfred Hitchcock's classic thriller really isn't about the romance, but those two are so charming that it's just the icing on the voyeuristic cake. —KS

LEONARDO DiCAPRIO and KATE WINSLET, Revolutionary Road (2008)
Jack and Rose who? In 2008's critically acclaimed Revolutionary Road, this duo proved that their movie magic only benefited from the 10 years the actors spent cultivating their post-Titanic titanic careers. —Sandra Gonzalez

ROBERT REDFORD and BARBRA STREISAND, The Way We Were (1973)
Few could have predicted the classic that would be born when The Sundance Kid and Fanny from Funny Girl got on the big screen together. And while some may argue the movie has not stood the test of time, we think the years gone by have done nothing to taint the magic of this film union. In short, your chemistry is lovely, Hubbell. —SG

TOM HANKS and MEG RYAN, Sleepless in Seattle (1993)
She'd long since met Harry, and he'd been a Big star for a few years when this twosome came together for the first time in an updated take on An Affair to Remember. So it was no surprise when the movie opened at No. 2 during its opening weekend, and eventually grossed more than $125 million domestically. Even more impressive, however, is how the unlikely pairing remains one of the best of that decade's romantic comedies. —SG

GEORGE CLOONEY and JULIA ROBERTS, Ocean's Eleven/Ocean's Twelve
Clooney's half-lidded gazes alone should be rated NC-17, but when you stick the actor opposite one of the leggiest and loveliest ladies in Hollywood, what else would result than 241 minutes (original + sequel) of (mostly) clothed cinematic, star-powered sexiness. We're really, really okay with all of that. —SG

STEVE McQUEEN and FAYE DUNAWAY, The Thomas Crown Affair (1968)
Now a cult film, this take on the bank heist movie didn't get great reviews when it was released but there was no question that the chemistry between McQueen and Dunaway was scene-stealing. —Abby West

MEL GIBSON and JULIA ROBERTS, Conspiracy Theory (1997)
While Gibson's performance as a manic, paranoid man who pulls Roberts' ADA into his crazy world may not have totally won over critics, it would go on to do extremely well at the box office — though not as well as Roberts' other movie that year, My Best Friend's Wedding. —AW

STEVE McQUEEN and ALI MacGRAW, The Getaway (1972)
McQueen and MacGraw's offscreen sparks (they fell in love during the shoot and married the next year) translated well enough onscreen as they play husband and wife in this intense, David Peckinpah-directed, on-the-run thriller. —AW

JACK NICHOLSON and FAYE DUNAWAY, Chinatown (1974)
Both Nicholson and Dunaway won Oscar nods for their performance in Roman Polanski's last U.S.-made movie — and one of cinema's enduring classics. —AW

PAUL NEWMAN and JULIE ANDREWS, Torn Curtain (1966)
The two Hollywood darlings failed to light up the screen as expected in this cold-war Hitchcock thriller, but they weren't the only things considered a disappointment about this lackluster excursion from the Master of Suspense. —AW

I'm torn between Paul/Elizabeth and Brad/Angelina.

People actually picked Brad and Angelia, Mr and Mrs Smith was the worst performance i have ever seen out of either of them!

However whenever these two get together its magic, as well as Kate and Leo!

Too many to pick... >_<

and Tom Hanks/Meg Ryan.

Jack Nicholson & Faye Dunaway-Chinatown
James Stewart & Grace Kelly-Rear Window
Paul Newman & Elizabeth Taylor-Cat on a Hot Tin Roof
Humphrey Bogart & Lauren Bacall-The Big Sleep