When two Hollywood stars unite, public fireworks happen as fans love to see two big names collide.
It doesn't hurt that both parties are usually outlandishly attractive.
It's like Cinderella and Prince Charming sprinkled with magic fairy dust.
Think of when Katie Holmes walked down the aisle with Tom Cruise - it was pandemonium as they were followed everywhere, given magazines covers and bestowed the catchy nickname TomKat.
Or when Angelina Jolie started romancing Brad Pitt; jaws dropped that these two A-listers were in love and starting a family together.
But some celebrity couples are not as well known because they either dated a long time ago or their sparks were brief.
Here is a look at the luminaries people may have forgotten were an item.
And scroll down to vote on who you thought made the cutest couple that should have stuck together.
TOM CRUISE & PENELOPE CRUZ
2001-2004
They met on the film Vanilla Sky and kept their relationship hush hush until they posed together at the premiere of her film Captain Corelli's Mandolin in August 2001.
The two star - who have similar last names - split in 2004.
She went on to marry Spanish actor Javier Bardem after they co-starred in Woody Allen's Vicky Cristina Barcelona.
Cruise also romanced another Latin lovely:Sofia Vergara.
They went on a few dates in 2005 after they were introduced by his friend Will Smith.
This was before she landed her hit series Modern Family in 2009 that made her a household name.
Tom Cruise and Penelope Cruz on the film Vanilla Sky and kept their relationship hush hush until they posed together at the premiere of her film Captain Corelli's Mandolin in August 2001. The two star - who have similar last names - split in 2004
Cruise and Sofia Vergara are seen on February 21, 2005 in Los Angeles.They went on a few dates in 2005 after they were introduced by his friend Will Smith
BRAD PITT & JULIETTE LEWIS
1989-1993
Juliette Lewis and Brad Pitt met in 1989 on the set of the 1990 film Too Young To Die then went on to co-star in Kalifornia.
The two split in 1993 and he went on to date Gwyneth Paltrow.
He wed Jennifer Aniston in 2000 then divorced in 2005. The star was married to his Mr & Mrs Smith costarAngelina Joliefrom 2014 until 2019.
In 1995 Brad said he still had feelings for Juliette.
'I still love the woman. There's some real genius there,' he shared.
'I had a great time with her. It was one of the greatest relationships I've ever been in. The problem is, we grow up with this vision that love conquers all, and that's just not so, is it?' he said.
But in 2006 she said of the star: 'He's not in my universe at all now. It seems like a high-school relationship because now he's a very famous person.
'I look at this person that I shared a bit of history with. I hope he finds happiness because I genuinely loved him. He's a very stand-up, good guy. … It was my longest relationship and we both lost our anonymity together.''
Juliette Lewis and Brad Pitt met in 1989 on the set of the 1990 film Too Young To Die then went on to co-star in Kalifornia. Seen in 1993
Juliette and Brad, left, in 1992. Jennifer Aniston and Brad, right, in 1999
In June she proved to fans that she is still in top shape as she modeled a one-piece swimsuit in a new photo shared to Instagram on Tuesday. The Cape Fear actress looked thin and toned in the dark blue bathing suit
JUSTIN BIEBER & KOURTNEY KARDASHIAN
2015
Kourtney Kardashian went on several dates with Justin Bieber in 2015.
They met through her younger half sister, model Kendall Jenner, who had worked with the pop king on a Calvin Klein underwear campaign.
When Justin was asked about the Kourtney dating rumors on The Bert Show, he joked that she was using him for headlines before complimenting the POOSH founder.
'She's great. I've known [the family] for years,' he added.
Kourtney Kardashian went on several dates with Justin Bieber in 2015. Seen at The Good Guy
They met through her younger half sister, model Kendall Jenner, who had worked with the pop king on a Calvin Klein underwear campaign
Fans were shocked when they saw Kourtney on a date with Justin because he is 15 years her junior.
But Kourtney's mother was thrilled as the romance helped drive interest in their reality TV show Keeping Up With The Kardashians.
Kourtney had just split from Scott Disick after he appeared to hook up with his ex, Chloe Bartolli. Kardashian and Disick stayed in touch, however, as they have three children together: Mason, Penelope and Reign.
Kourtney is now married to Travis Barker and together they have newborn son Rocky Thirteen while Justin is expecting his first child with wife Hailey Bieber.
Kourtney is now married to Travis Barker and together they have newborn son Rocky Thirteen. Seen on July 6
Justin is expecting his first child with wife Hailey Bieber. Seen in 2021
JESSICA SIMPSON & TONY ROMO
2007-2009
Jessica Simpson first started dating football player Tony Romo in November 2007.
The blonde beauty had just left Nick Lachey with whom she starred in The Newlyweds.
And Tony was a top football star with the Dallas Cowboys, serving as quarterback.
Cowboy fans were hard on singer Jessica as they accused her of hurting Tony's performance.
Then the rumours started swirling that he was cheating on the star, who has appeared in the movies Dukes Of Hazzard and Employee Of The Month.
Jessica Simpson first started dating football player Tony Romo in November 2007. The blonde beauty had just left Nick Lachey with whom she starred in The Newlyweds. Seen in 2008
Romo was also upset that she was spending time with her ex John Mayer. She wrote in her memoir Open Book: 'Tony accused me of seeing John behind his back. I hadn't cheated on Tony at all, but I could not lie and say I hadn't even seen him.' Seen in 2009
Romo was also upset that she was spending time with her ex John Mayer.
She wrote in her memoir Open Book: 'Tony accused me of seeing John behind his back. I hadn't cheated on Tony at all, but I could not lie and say I hadn't even seen him.'
Romo reportedly broke up with Simpson over email in 2009.
She went on to marry Eric Johnson, with whom she has three children: Maxwell Drew, Ace Knute and Birdie Mae.
Romo married former Miss Missouri Candice Crawford in May 2011.
JENNIFER ANISTON & JOHN MAYER
2008-2009
Jennifer Aniston and John Mayer met in 2008 at an Oscar party.
They went on to become inseparable for a year as she followed him on tour, took him to premieres, and made him her plus one at the Oscars in 2009.
They eventually split due to their age difference: she is 55 and he is 46.
'I'll always be sorry that it didn't last,' John told Playboy in 2010 about dating the popular Friends actress.
Jennifer Aniston and John Mayer met in 2008 at an Oscar party. They went on to become inseparable for a year as she followed him on tour, took him to premieres, and made him her plus one at the Oscars in 2009
They eventually split due to their age difference: she is 55 and he is 46. 'I'll always be sorry that it didn't last,' John told Playboy in 2010 about dating the popular Friends actress
Aniston, who looked stunning in red in June, appears to be single at the moment
'In some ways I wish I could be with her. But I can't change the fact that I need to be 32,' he added.
John said that he wanted to go out and do things and not sit at home in Los Angeles with Aniston.
'I want to dance. I want to get on an airplane and be like a ninja. I want to be an explorer. I want to be like The Bourne Identity. I don't want to pet dogs in the kitchen,' he shared.
Aniston is known for having several dogs.
RYAN REYNOLDS & ALANIS MORISSETTE
2002-2007
Alanis Morissette and Ryan Reynolds met at Drew Barrymore's 27th birthday party in 2002.
They became a high-profile couple as they cuddled when they hit red-carpet events together.
In June 2004, they got engaged.
'We have the perfect combination of compatibility and incompatibility that makes the relationship very passionate. It's perfect. I think it's about stretching each other,' Morissette told People.
They split for a while then got back together in July 2004.
In 2005 they split
Alanis Morissette and Ryan Reynolds met at Drew Barrymore's 27th birthday party in 2002. They became a high-profile couple as they cuddled when they hit red-carpet events together. Seen in 2003
In June 2004, they got engaged. 'We have the perfect combination of compatibility and incompatibility that makes the relationship very passionate. It's perfect. I think it's about stretching each other,' Morissette told People. Seen in 2004
'They remain close friends and continue to have the utmost love and admiration for each other. They ask that their privacy be respected surrounding this personal matter,' their reps shared in a statement to People.
Her 2008 album, Flavors of Entanglement, mentioned the split.
She told the Los Angeles Times: 'I was a full-blown love addict, so it was like, "I can't keep doing this, my body can't take it." For someone who is a love addict, [breakups are] debilitating.'
She added, "I've been on a constant journey toward finally surrendering and hitting the rock bottom that I've been avoiding my whole life. So this was a huge, critical juncture for me. Everything broke, and it was an amazing and horrifying time."
Reynolds then wed Scarlett Johansson, divorce, then married Blake Lively.
In 2010, Alanis wedMario John Treadway, better known by his stage name, Souleye, an American hip hop artist.
CAMERON DIAZ & JARED LETO
1999-2003
Cameron Diaz and Jared Leto started dating in 1999.
There were rumors they were engaged as she wore a big diamond ring to the Golden Globe Awards in 2003, but she denied it.
They split later in 2003.
Both seemed to put their career over marriage and a baby carriage.
'I don't think it is necessary to walk down the aisle in a white dress to maintain a relationship," she said to The Mirror around the time of her split from Leto.
Cameron Diaz and Jared Leto started dating in 1999. There were rumors they were engaged as she wore a big diamond ring to the Golden Globe Awards in 2003, but she denied it. They split later in 2003. Seen in 2000
'It's great to have a partner, but I don't see how a piece of paper means anything at all. I wouldn't be unfulfilled if I didn't marry.'
He admitted to Details magazine that he did not want to become a husband.
'I don't really believe in settling down,' Leto said. 'That term implies that the current path I'm on isn't valid. It's not always about living your life the way people have lived before you.'
Cameron started dating musician Benji Madden in 2014 and they wed in 2015. They have two children: Raddix and Cardinal.
BEN AFFLECK & GWYNETH PALTROW
1997-2000
Gwyneth Paltrow started dating Ben Affleck in 1997 after she broke off her engagement from Brad Pitt.
She has since said that Ben was great in bed.
When on a podcast last year she was asked to compare her former fiance Brad Pitt with Affleck.
'Brad was like the sort of major chemistry, love of your life, kind of, at the time and then Ben was, like, technically excellent,' she laughed.
The Oscar winner then added: 'I can't believe my daughter is listening to this!'
Gwyneth is now married to AHS producer Brad Falchuk.
And Affleck is reportedly estranged from his wife of two years, Jennifer Lopez.
Gwyneth Paltrow and Ben Affleck dated from 1997 until 2000
When on a podcast last year she was asked to compare her former fiance Brad Pitt with Affleck. 'Brad was like the sort of major chemistry, love of your life, kind of, at the time and then Ben was, like, technically excellent,' she laughed
SANDRA BULLOCK & MATTHEW McCONAUGHEY
1996-1998
Matthew McConaughey and Sandra Bullock met on the set of the 1996 movie A Time to Kill.
Soon after they started dating but their kept their romance under the radar for the most part.
Sandra Bullock and actor Matthew McConaughey attend the In Love and War Los Angeles premiere in January 1997 at DGA Theatre in Hollywood
They met on the 1996 film A Time To Kill
They reportedly dated for two years.
They went to movie premieres together like her film In Love And War.
She was a much bigger star than him at the time as people were still trying to figure Matthew out.
It has been claimed that they ended their romance in 1998 over dinner at his house.
She has said kind things about the Dallas Buyers Club star: 'There’s a great amount of respect and love.
'I feel very cared for by Matthew.
'No matter where he is in his life or where I am in mine—he could be married—I know we would stay close,' she said.
He has been wed to Camila Alves since 2012.
Bullock sadly lost her partner, photographer Bryan Randall, in August 2023 to ALS. He was only 57. They had started dating in 2015.
'Bryan chose early to keep his journey with ALS private and those of us who cared for him did our best to honor his request,' a statement from his family read.
'We are immensely grateful to the tireless doctors who navigated the landscape of this illness with us and to the astounding nurses who became our roommates, often sacrificing their own families to be with ours.'