The victim: Kim Kardashian at Tao Nightclub at The Venetian Las Vegas to celebrate her 33rd birthday.
The model creeped up on Sienna Miller at the Costume Institute Gala for the 'PUNK: Chaos to Couture' exhibition at the Metropolitan Museum of Art in New York City.
Pegg pranked co-stars Paula Patton, Tom Cruise and Léa Seydoux at the Mission: Impossible - Ghost Protocol premiere in London.
The singer snuck into fans' selfie during the 19th Annual Miami Make-A-Wish Ball at the InterContinental Hotel in Miami, Fla.
The victims: Liam Hemsworth, Elizabeth Banks, Nina Jacobson and Jena Malone, attending a special screening of The Hunger Games: Catching Fire in New York City.
The victim: Leslie Mann, attending the premiere of Anchorman 2: The Legend Continues in London.
Frédéric Prinz von Anhalt got photobombed by the Nashville star at the 71st Annual Golden Globe Awards in Beverly Hills.
Clooney tried to steal the spotlight from Steven Spielberg, Jessica Seinfeld and Jerry Seinfeld at the USC Shoah Foundation Institute 2013 Ambassadors for Humanity gala in New York City.
The actress teased her husband David Cross and pal Amy Poehler at the Sleep No More New Year's Eve 2014 Party in New York City.
Only in the Big Apple! The Scrubs actor photobombed a random newlywed couple in the streets of NYC, as captured by professional shutterbug Sascha Reinking.
The Newsroom star has mastered the art of photobombing.
One week before the Breaking Bad series finale aired, the two costars tried to lighten the mood with their hilarious antics on the red carpet.
Step aside Joe Jonas! The youngest Jo Bro reunited with his close friend at the Teen Choice Awards in Los Angeles. But Joe just had to get in the middle of things.
Shortly after winning a Teen Choice Award, the Pitch Perfect star unknowingly posed with costars Anna Camp and Skylar Astin.
Her Majesty was upstaged by Princess Eugenie at day one of the Royal Ascot races.
The victim: The Dawson's Creek star made a wide-eyed expression behind Anne Hathaway while walking the 2013 Met Gala red carpet.
With the help of James Corden, Stone photobombed her then-boyfriend Andrew Garfield, Eleanor Matsuura and Neil Stuke.
The victims: Katy Perry and then-husband Russell Brand.
The victims: Ellen DeGeneres and wife Portia de Rossi.
The Victims: Actors Robert Pattinson, Cam Gigandet, Taylor Lautner and Kristen Stewart on stage at the 2008 MTV Video Music Awards.
The victims: Ian Somerhalder and his very attractive friend.
The victims: Whoever these people are.
The Victims: Justin Bieber and Ke$ha during dress rehearsal at Staples Center.
The victims: Brokeback Mountain director Ang Lee and Uma Thurman.