Maria Shriver and Arnold Schwarzenegger

Demi Moore and Ashton Kutcher. Kim Kardashian and Kris Humphries. Jennifer Lopez and Marc Anthony. Maria Shriver and Arnold Schwarzenegger. Those are just some of the celebrity couples who called it quits in 2011 — and we still have a month left to go.

Look back at our list of some of the year's biggest splits, and tell us which breakup surprised you the most.

Demi Moore divorcing Ashton Kutcher; he responds on Twitter

JANUARY
Mila Kunis and Macaulay Culkin called it quits after eight years together. The pair, who was notoriously private, reportedly split late last year, but kept it under wraps while Kunis promoted Black Swan.

Taylor Swift and Jake Gyllenhaal ended their short-lived romance after two months. The two, who were first spotted together in October 2010, spent Thanksgiving weekend together at his sister and brother-in-law Maggie Gyllenhaal and Peter Sarsgaard's home.

FEBRUARY
There was no happily ever after for Olivia Wilde, who split from her husband, Italian prince and filmmaker Tao Ruspoli. She filed for divorce a month later and it was finalized in September. The couple eloped in 2003 when Wilde was 18.

Jude Law and Sienna Miller broke up for the second time, two years after reconciling. They first started dating in 2004 after meeting on the set of Alfie and got engaged that Christmas. They broke up in 2006 after Law admitted that he had cheated on the actress with his children's nanny.

Ashlee Simpson filed for divorce from Pete Wentz after three years of marriage. The two, who married in May 2008 in a ceremony officiated by her father, Joe Simpson, have one son, Bronx Mowgli, who turns 3 on Sunday. Simpson is currently dating Boardwalk Empire star Vincent Piazza.

Rosie O'Donnell and Tracy Kachtick-Anders, an artist and activist, broke up after dating for a little more than a year. They have 10 children between them: O'Donnell has four kids with ex Kelli Carpenter and Kachtick-Anders has six.

Maria Shriver files for divorce from Arnold Schwarzenegger

MARCH
Melissa Gilbert and Bruce Boxleitner split after 16 years of marriage, and the actress filed for divorce in August. They have a 16-year-old son, Michael, who is named after the her Little House on the Prairie co-star Michael Landon. Gilbert also has a son with ex-husband Bo Brinkman, and Boxleitner has two sons with ex-wife Kathryn Holcomb.

Justin Timberlake and Jessica Biel called it quits after four years together, but there may be hope yet! They have recently been spotted out and about together, but Biel is keeping mum. "A girl doesn't kiss and tell," Biel said in the December issue of Elle.

Joe Jonas and Twilight actress Ashley Greene split a few months shy of their one-year mark. No word on if he dumped her over the phone.

Incumbent Sexiest Man Alive (though not in many people's eyes) Bradley Cooper and Renée Zellweger, who met on the set of the thriller Case 39, ended their two-year relationship. In January, when Cooper's father died, Zellweger pulled out of the Golden Globe awards, where she was scheduled to present, to be with him. Cooper was recently linked to Jennifer Lopez, but he told People that he's single.

MAY
Jennifer Love Hewitt and director Alex Beh broke up after dating for less than a year. Hewitt — whose list of past loves include Jamie Kennedy, Ross McCall and Carson Daly — quickly moved on to Eagle Eye actor Jarod Einsohn.

Maria Shriver and Arnold Schwarzenegger separated after 25 years of marriage after Schwarzenegger admitted fathering a child with a longtime member of their household staff. Shriver filed for divorce in July. They have four children together.

The Social Network's Andrew Garfield and Raising Hope star Shannon Woodward ended their three-year relationship, reportedly due to work commitments. Garfield has since been spotted out with his Amazing Spider-Man co-star Emma Stone.

JUNE
Demi Lovato and Wilmer Valderrama split after a few months of dating, during which Lovato sought treatment for "physical and emotional issues." The couple's relationship may be on again: The actress-singer was photographed kissing Valderrama outside his house earlier this month.

Runaway bride! Crystal Harris called off her nuptials to Hugh Hefner five days before their wedding. The 25-year-old later said the 85-year-old Playboy mogul's lifestyle wasn't one she wanted and claimed sex with him lasted "like, two seconds." Don't feel too bad for Hef. He has two new gal pals: Anna Sophia Berglund and November Playmate Shera Bechard.

Buzz Aldrin filed for divorce from his third wife, Lois Driggs Cannon, after 23 years. The two wed on Valentine's Day in 1988 and have no children.

Paris Hilton and her beau of a year Cy Waits split because the nightclub owner supposedly did not like living in the spotlight. He was seen in the heiress' failed comeback reality series The World According to Paris.

George Clooney and Italian actress Elisabetta Canalis broke up after two years. Conspiracy theorists will note that this happened a month after Canalis said in an interview that she will get married one day — and we all know that Clooney's an eternal bachelor. Canalis went on to compete on Dancing with the Stars and Clooney is now dating Stacy Keibler — another Dancing alum.

David Duchovny and Téa Leoni separated for the second time in three years. The couple, who wed in 1997 and have two kids, first split in October 2008, shortly after Duchovny completed sex-addiction treatment. They were spotted together in June 2009 and confirmed their reconciliation that September.

Brad Womack's second stint on The Bachelor had no happy ending either. He and Emily Maynard called off their engagement three months after the season finale. Although they were still engaged during the After the Final Rose special, Maynard, who lives in North Carolina, made it clear she wasn't ready to move to Womack's hometown of Austin.

Jennifer Lopez and Marc Anthony split

JULY
Jennifer Lopez and Marc Anthony split after seven years of marriage and two kids. The power couple quietly married in June 2004, five months after Lopez called off her engagement to Ben Affleck. This was her third marriage and his second.

Real Housewives of Beverly Hills star Taylor Armstrong filed for divorce from her husband of five years Russell, with whom she has a 5-year-old daughter Kennedy. A month later, he committed suicide, prompting Bravo to re-edit footage they had shot for the second season. The couple's marital troubles were well-chronicled during the first season.

AUGUST
The Talk creator and co-host Sara Gilbert and partner Allison Adler, a Glee writer, split after 10 years and two kids together. Gilbert rarely spoke about their relationship while they were together, opting to exclude Adler's name from her The Talk bio when it premiered last year.

Strike out! Minka Kelly and Derek Jeter called it quits after three years of dating. Just a month earlier, Kelly watched the New York Yankee superstar join Major League Baseball's 3,000-hit club.

SEPTEMBER
Tareq Salahi filed for divorce from his wife, Real Housewives of D.C. star and fellow White House party crasher Michaele Salahi, accusing her of being "in an adulterous relationship" with Journey guitarist Neal Schoun. A week prior, Tareq alerted police that he feared his wife had been kidnapped. Turns out, she had gone to Memphis with Schoun, who is an ex-boyfriend of hers.

Kat Von D and Jesse James broke up for the second time in two months, but it sounds like this time it's for good. Von D wrote on Facebook earlier this week that James cheated on her with 19 women during their year-long relationship. The pair started dating in summer 2010, shortly after news of James' cheating led to his divorce from Sandra Bullock. At the time, Von D said she wasn't worried about the motorcycle builder's past infidelities.

Kim Kardashian divorcing Kris Humphries

OCTOBER
Following a five-month, whirlwind romance that included lounging on Steven Spielberg's yacht in Monte Carlo, Blake Lively and Leonardo DiCaprio called it quits. DiCaprio new lady love is model Madalina Ghenea.

Nicole Scherzinger ended her four-year relationship with race car driver Lewis Hamilton. Distance was to blame: The X Factor judge is based in Los Angeles while Hamilton has a house in Switzerland and travels the world frequently.

After a lavish televised wedding and 72 days of marriage, Kim Kardashian filed for divorce from pro basketball player Kris Humphries. Kardashian later flew to Humphries' Minnesota hometown and the couple met with the pastor who officiated their wedding, but according to her mother, Kris Jenner, the trip was for closure, not to discuss a reconciliation. Jenner also insists that her daughter did not make a penny off the wedding.

NOVEMBER
Hipsters rejoice! New Girl star Zooey Deschanel and her husband, Death Cab for Cutie frontman Ben Gibbard, separated after two years of marriage. The two met three years ago when their mutual music manager introduced them.

Bachelor and Bachelor Pad 2 couple Vienna Girardi and Kasey Kahl broke up after nine months of dating. Girardi was previously engaged to Jake Pavelka after winning his season of The Bachelor. Kahl unsuccessfully competed for Ali Fedotowsky's affections on the sixth season of The Bachelorette. Looks like he'll need to find another heart to guard and protect.

Heather Locklear and Jack Wagner, who played on-again, off-again lovers, on the original Melrose Place, called off their three-month engagement. The actress was previously married to Tommy Lee and Richie Sambora, while Wagner was once married to his General Hospital co-star Kristina Wagner. They had been together since 2007.

Following months of rumors, cheating allegations on his part and unfollowing each other on Twitter, Demi Moore and Ashton Kutcher confirmed the end of their six-year marriage. "As a woman, a mother and a wife there are certain values and vows that I hold sacred, and it is in this spirit that I have chosen to move forward with my life," Moore said. Kutcher reportedly had a one-night stand with a 22-year-old named Sara Leal on their sixth wedding anniversary.