His studios were crammed with sketches and outlines of countless portraits. The famous painter preferred to work with models who would be around for the entire day, like family members, wives and children. Sitting still for Picasso was part of the normal daily routine.

Picasso met Jacqueline Roque in 1952 at the Madoura pottery workshop where his ceramics were baked. When Picasso married her in 1961, he was already 80 years old, and she was 34. She helped him in his work while protecting him against the outside world, remaining his companion, muse and model until his death in 1973. He created over 400 portraits of her.

One of his muses was 19-year-old Sylvette David from England, whom Picasso had met in 1954. Totally enraptured by the young blonde woman, he produced 50 drawings, paintings and sculptures of her within one month only. Her trademark ponytail became trendy in the 1950s.

Picasso's friends also appear in his oeuvre, including painter Amadeo Modigliani (left, with Picasso, center, and art critic André Salmon, right). This picture was taken by Jean Cocteau in 1916 in front of their favorite coffee shop in Paris, Café de la Rotonde. Cocteau was also portrayed several times by Picasso.

Throughout his life, Pablo Picasso developed close friendships with his art dealers, especially Daniel-Henry Kahnweiler. In 1907, the German-French art historian opened a small Gallery in Paris, signing exclusive contracts with artists who were to become famous later on - among them Picasso. In 1910, he painted this Cubist portrait of Kahnweiler.

The interior world of his studio fully sufficed for an obsessed artist like Picasso. Simple vases, bowls or the bust of a woman served as models for sketches or a huge oil painting. As a painter and drawer, he remained faithful to his themes for a long time as they repeatedly popped up in different versions in his works.

In spite of all his hard work, Picasso did find time for humor, producing cartoons just for fun. In this case, he embellished a pin-up picture out of a film magazine of Esther Williams with a portrait sketch of his artist friend Juame Sabartés. The Hollywood actress became famous for swimming scenes in her films. Among her admirers was also Picasso.

Following numerous love affairs, the young painter met Russian ballerina Olga Khokhlova in 1917, and married her. She voluntarily gave up her career at the world famous "Ballets Russes" - and facilitated his access to exclusive Paris circles. The Picasso exhibition at London's National Portrait Gallery, held until February 5, 2017, devotes an entire room to portraits of her.