© Getty Images

King George III -

Imagine this: it's date night, and you've got tickets to 'Hamilton.' You're enjoying the show, when suddenly a very special guest shows up on stage. It's Prince Harry making a star appearance as King George III. You're stunned, of course!

© Getty Images

The fab four -

In 2018, Kate Middleton surprised with an appearance at the Royal Air Force centenary in London. There, she reunited with the “Fab Four.”

© Getty Images

A trip to Balmoral -

Also in 2018, Prince Philip stepped out with the Queen and granddaughter Zara Tindall. They visited Balmoral Castle.

© Getty Images

Fashion Week -

Perhaps one of the biggest surprises, the Queen showed up to London Fashion Week. She was right by the runway with Vogue editor Anna Wintour.

© Getty Images

Birthday girl -

For her 92nd birthday, the Queen pulled up to the Royal Albert Hall stage. She surprised audiences at home and in the crowd, who sung a joyous 'Happy Birthday to You.'

© Getty Images

Sisterly love -

Kate Middleton and her sister, Pippa (pictured), made a surprise visit to Sandringham House. They also attended a Sunday morning service at St. Mary Magdalene Church.

© BrunoPress

Walk about Windsor -

Harry and William surprised crowds and took a walk around Windsor Castle in May 2018.  

© Getty Images

Breaking the ice in Belfast -

Prince Harry and Meghan Markle made a surprise visit to Belfast. They were there to meet members of the public, as well as to visit Belfast’s biggest sites.

© Getty Images

William in Toronto -

Prince William made a surprise appearance in Toronto, albeit through a pre-recorded video clip. He spoke at a youth mental health summit, offering some special words of wisdom.

© Getty Images

Charles and Harry -

Prince Charles and Prince Harry made a rare surprise appearance in February 2018. The duo showed up to an event for The Prince of Wales’s International Sustainability Unit.

© Getty Images

Middleton at the Anna Freud National Centre -

Kate Middleton surprised crowds at a conference hosted by the Anna Freud National Centre for Children and Families.

© Getty Images

Christmas party -

Staff Christmas parties aren’t all that, unless Meghan Markle makes a surprise appearance. She showed up to the Queen’s staff Christmas party in 2017.

© Getty Images

Partying with Paddington -

In 2017, Kate Middleton made an unannounced visit to Paddington station, where a charity benefit was taking place.

© Getty Images

Big anniversary -

The Queen celebrated the 150th anniversary of the Aboyne Highland Games by making a surprise appearance.

© Getty Images

A very special Father's Day -

In 2017 Princess Anne honoured Father's Day in a very special way. She visited fathers who were working on a 'DIY SOS' project, renovating the house of a disabled father.

© Getty Images

On the market -

London’s Borough Market was hit with a shocking terrorist attack in 2017. When the market reopened, Prince Harry surprised crowds to show support.

© Getty Images

Thanking the police -

Similarly, Prince William surprised Manchester police to give his thanks following the terrorist attack that struck the city.

© Getty Images

Battling Batten - Prince Harry surprised Ollie and Amelia Carroll, two children who both suffer from Batten disease. The prince cracked jokes and played around with the kids.

© Getty Images

A royal thank you -

Prince Harry sure loves a surprise. In April 2017, he made a surprise visit to double amputee Duncan Slater (left), so as to give his thanks and pay respect.

© Getty Images

Military entourage -

The Duke of Kent shocked residents at Harewood House with a surprise visit, complete with military entourage.

© Getty Images

Sophie surprises guests -

Sophie, Countess of Wessex, made a surprise visit to Leeds Children’s Hospital back in 2013. She was there to support Nikita Chidwick, who was due to undergo an operation.

© Getty Images

Up in the air -

Young pilots Libby and Michael had the surprise of a lifetime when Prince Philip came to say hi. His Royal Highness made a surprise visit to the British Airways HQ.

© Getty Images

Schoolin' 'em -

Imagine sitting down for school dinner, turning your head and seeing Prince William. The royal visited John Henry Newman School for an unexpected appearance.

© Getty Images

Chatting with the young ones -

In 2015, Prince Harry paid a surprise visit to the Duke of York’s Royal Military School in Kent. There, he toured and chatted with excited pupils.

© Getty Images

Respecting radio -

In 2014, the Duke of Kent made an unexpected appearance in Swindon. There, he presented the Queen's Award to Shirley Ludford, manager of Radio Swindon 105.5.

© Getty Images

A big thank you to staff -

Prince William made a surprise visit to the Commonwealth Games in 2014. He thanked workers and staff of the Games.

© Getty Images

Camilla up north -

The Duchess of Cornwall made not one, but two surprise visits in Edinburgh.

© Getty Images

Harry in the booth -

In 2014, Prince Harry shocked staff when he showed up to a youth centre recording studio in Nottingham.

© Getty Images

A personal royal approval -

A few years ago, Prince Charles gave a personal royal approval to newlyweds in Ayr, Scotland.

See also: Casual wear: When royals dress down 

© Getty Images