18 pictures that show what celebrities wore to meet members of the British royal family

The Queen seemingly wore a black off-the-shoulder gown with white gloves, a tiara, and diamond jewelry, while Monroe opted for a shining dress with thin straps and a sweetheart neckline. She also wore gloves that seemingly matched her outfit.

They met during a performance of "The Battle of the River Plate" at the Empire Theatre in Leicester Square, London.

Streep specifically wore the white, long-sleeved outfit and matching short gloves for a showing of "Kramer vs. Kramer" in London, England.

The actress completed her look with an updo hairstyle and metallic earrings.

Queen Elizabeth II donned a similar style for the event: a white long-sleeve dress embellished with sequins. She also wore a fur shawl, short gloves, and statement jewels.

That year, a royal gala was held at the Manchester Opera House in England to celebrate the 21st anniversary of Charles' The Prince's Trust charity. Backstage, the Prince of Wales was greeted by celebrities including Jennifer Aniston, Geri Halliwell, and Melanie Brown.

The two Spice Girls rocked their signature styles. Halliwell wore a white tank top lined with a plunging neckline and blue sequin details, while Brown wore a plaid bralette underneath a coral blazer.

Aniston went with a more subtle look that included a navy sleeveless dress, minimal makeup, and one of her signature haircuts.

The Queen attended the Spice Girls' 1997 performance at London's Victoria Palace Theatre in a metallic, short-sleeved dress, mid-length gloves, and gold jewels.

The Spice Girls wore bolder looks. Emma Lee Bunton wore a white sleeveless gown, while Victoria Beckham chose a brown strapless dress with a short slit down the side.

Melanie C wore the most casual look of the group, which included a tank top, red pants, and sneakers.

Halliwell shook the Queen's hand while wearing a white halter gown, and Brown sported an animal-print bra, open shirt, and velvet pants.

The two actors met the Queen at the premiere of "The Parent Trap." Quaid looked dapper in a classic suit and bow tie, while Richardson wore a white dress with sheer sleeves and crystal hair clips.

The Queen also shined in a sparkling long-sleeved top, yellow skirt, and white gloves.

The Queen and Lopez met at the Dominion Theatre in London after that year's Royal Variety Performance. Lopez wore a green halter-style dress, a statement necklace, and a sleek hairstyle.

The Queen wore a semi-sheer blue dress that was covered in sequins and floral details. Of course, she also sported her signature gloves.

The singer paired his pants with a black blazer and white button-up shirt.

The Queen, on the other hand, wore a sparkling white dress and diamond jewelry.

The two royals also got dressed up for the occasion. Princess Beatrice paired a floral dress with black tights and flats, while Princess Eugenie chose a sleeveless green gown with a red bow and purple heels.

The musicians met the princes during a party William and Harry held after a Wembley Stadium concert.

West wore a gray-toned blazer over a tan shirt and red tie. He also wore white shutter shades, which were all the rage in the early aughts. Diddy also embraced the era's trends by wearing a navy jacket over a graphic T-shirt.

Harry and Prince William opted for more traditionally royal looks, which included button-up shirts, neutral-colored jackets, and casual pants with belts.

Cyrus, who was a host of that year's Royal Variety Performance, wore an orange gown with a floor-length skirt and a plunging neckline. The dress also had a criss-cross belt across her waist and a tiny cutout.

The Queen wore a sparkling black shawl over a matching dress and accessorized with black gloves.

Her look that night included a red latex dress with a high neckline and puffy sleeves. Lady Gaga also wore pointed red boots, curled blonde hair, and exaggerated eye shadow embellished with makeup jewels.

The actress met the Duchess of Cambridge in Santa Barbara, California, during the royal's first joint trip with Prince William to the US after getting married.

Witherspoon wore a sleeveless orange dress with ruffles across its bodice, as well as brown wedge sandals. Middleton sported a white dress that day with a blue knit overlay and matching pumps.

The model's look included a sleeveless dress with fabric that wrapped around her waist and tied into a bow across her shoulder to create an open back. She also seemingly wore a leather belt as a headband.

The Prince of Wales and the Duchess of Cornwall sported more subdued looks. The prince wore a blue suit and Camilla wore a white dress with a matching bedazzled jacket.

The two met during the Winter Whites Gala In Aid Of Centrepoint, held in London, England. The Duke of Cambridge donned a simple black suit and bow tie, and Swift wore a cream-colored dress with a pleated skirt and bedazzled semi-sheer top.

The musician also wore a curly updo hairstyle and red lipstick.

The actress and philanthropist was awarded an honorary damehood for her work with UK foreign policy to end war zone sexual violence.

Jolie wore a gray-toned suit jacket, below-the-knee skirt, and open-toe heels for the event. The Queen's look included a light-orange dress, black heels, and pearls.

Styles and Middleton shook hands at the 2014 Royal Variety Performance.

The musician wore an animal-print jacket over a black button-up and matching pants, while Middleton wore a black dress with lace sleeves and diamond earrings.

Lady Gaga and Tony Bennett were pictured meeting the Duke of Sussex before a gala concert in London, England.

Bennett went with a classic black suit and tie for the performance, while Lady Gaga wore a metallic long-sleeved dress with a plunging scoop-style neckline.

The musician also had her hair tied in a bun and wore jewels across her eyebrows.

Beyoncé's asymmetrical dress had one off-the-shoulder sleeve and another short sleeve. Her yellow-gold gown also had a floor-length skirt with a daring slit on one side. Jay Z coordinated his outfit by wearing a black tuxedo and bow tie.

Markle greeted the musical couple in a $4,343 Jason Wu dress with semi-sheer details, and Prince Harry wore a suit and bow tie similar to Jay-Z's.