Westeros and the United Kingdom collided this week when Queen Elizabeth stopped by the set of Game of Thrones . While she was there, she met cast members Rose Leslie, Kit Harington, Sophie Turner, Lena Headey and more! That got us thinking: even when they're not from the seven kingdoms (like these Game of Thrones stars), celebrities are often considered to be Hollywood royalty, right? They have massive fan bases, their public appearances can cause a frenzy, and they live lavishly with the money they make. They even sometimes receive gold for their work — in the form of statues and awards, of course. But what happens when they meet actual royalty? Scroll down and to see even how huge Hollywood stars get a little starstruck sometimes.
Tom Hardy casually exchanged words at the Audi Polo Challenge in Ascot, England in June 2014.
In December 2013, Adele was made a Member of the Most Excellent Order of the British Empire for her contribution to music. She took part in an investiture service with Prince Charles.
Prince William sat next to Taylor Swift  at the Winter Whites Gala in London in November 2013.
In June 2014, Helen Mirren  attended the Audi Polo Challenge in Ascot, England, where she met Prince William.
Reese Witherspoon  and Kate Middleton shook hands in Beverly Hills at the reception to mark the launch of Tusk's US Patron Circle in July 2011.
The queen of pop, Madonna , met the Queen of England at the November 2002 world premiere of Die Another Day in London.
Clive Owen  and Prince Harry chatted at the Audi Polo Challenge in Ascot, England in June 2014.
Prince William met Pharrell Williams in July 2006 at the Audi Polo Challenge in Midhurst, England.
Mila Kunis , Ashton Kutcher , and Princess Beatrice of York all spent the day together in Saint-Tropez in June 2013.
Lady Gaga  was given the opportunity to meet Queen Elizabeth after the Royal Variety Performance in Blackpool, England, in December 2009.
Enrique Iglesias met Queen Elizabeth at the Royal Variety Performance in Liverpool in December 2007.
Queen Elizabeth and Bette Midler made each other's acquaintance after the Royal Variety Performance in December 2009 in Blackpool, England.
David Beckham , Prince Harry, and Prince William all posed together in June 2010 in Johannesburg, South Africa, during the FIFA World Cup.
Serena Williams met Queen Elizabeth II in June 2010 at Wimbledon  in London.
Kate Middleton had a conversation with Tom Hanks  at the 2011 BAFTA Brits to Watch Event in LA in July 2011.
Nicole Kidman  and Kate Middleton spoke at the 2011 BAFTA Brits to Watch Event in LA in July 2011.
Barbra Streisand and Prince William spoke at the July 2011 BAFTA Brits to Watch Event in LA.
Prince William joined Taylor Swift  and Jon Bon Jovi on stage for a performance of "Livin' on a Prayer" at Kensington Palace in November 2013.
Jennifer Lopez  met newlyweds Prince William and Kate Middleton at the July 2011 BAFTA Brits to Watch Event in LA.
Katie Couric met Queen Elizabeth at a garden party at Buckingham Palace in May 2012.
Damian Lewis got to meet Queen Elizabeth at a reception for the British film industry in Berkshire, England, in April 2013.
Carey Mulligan  met Queen Elizabeth at a reception for the British film industry at Windsor Castle in April 2013.
Prince William attended a reception in July 2011 to mark the launch of Tusk's US Patron Circle in Beverly Hills, where he met Reese Witherspoon .
Princess Beatrice of York posed with MTV star Colton Haynes and Glee star Matthew Morrison  at the annual Serpentine Gallery party in London in June 2013.
Anne Hathaway  and Julie Andrews met Princess Beatrice at the London premiere of The Princess Diaries 2: Royal Engagement in September 2004.
Princess Beatrice attended the UK premiere of The Aviator in December 2004, where she met Leonardo DiCaprio .
Princess Eugenie and Princess Beatrice posed with Naomi Campbell  at London Fashion Week in September 2008.
Prince William posed for photographs with Jon Bon Jovi and his family at a gala at Kensington Palace in November 2013.
Prince Harry and LL Cool J took a photo together in May 2009 at the Veuve Clicquot Manhattan Polo Classic in NYC.
Queen Elizabeth met her Hollywood impersonator, Helen Mirren , in May 2009 at a performing arts reception at Buckingham Palace.
Prince William met Tom Hiddleston at the UK premiere of War Horse in January 2012.
Paul McCartney was given the opportunity to meet Queen Elizabeth II at the Diamond Jubilee Concert in London in June 2012.
Queen Elizabeth met Will.i.am in June 2012 at the Diamond Jubilee Concert in London.
Princess Beatrice and Salma Hayek  met each other in November 2012 at the British Fashion Awards in London.
One Direction's Niall Horan met the queen at Buckingham Palace in March 2014.
The Game of Thrones cast met Queen Elizabeth and Prince Philip on set.