Jean Clouet (c. 1485-1541), a Flemish artist who emigrated to France around 1515, is the artist who turned the portrait into a specifically French art form during the sixteenth century. Clouet appeared on the royal accounts as a well-pensioned artist in 1516 and remained there until his death, when his position and pension passed to his artist son François (c. 1515-1572), who continued in his father's footsteps of providing portraits for the court's nobles. Both Jean and François sketched drawings, in red and black chalk, of their subjects in preparation for oil paintings. The drawings were usually a three-quarters view of the subject's shoulders and head and were kept "on file" in the studio long after the painted portrait was completed. The artists' output was prodigious: there are 363 drawings preserved in the museum of Chantilly, dating from 1510-1550 (primarily Jean's work) and 569 at the Cabinet des Estampes, dating from 1550-1600 (primarily by François's hand, although by the second half of the century minor artists were producing portraits of their own, careful to copy the technique and style popularized by the Clouets).
Art historians debate whether these drawings were used solely in preparation for the painting of oil portraits (the fact that many of the originals have notes about color, for example "Sleeves green," "Nose red," written on them supports this thesis) or were fashioned as works in their own right. What is certain it that copies of these drawings, traced by the artists' assistants, soon became hot items. Collections of them were bound together in books called albums, of which twenty or so survive. These albums were often sent as gifts to heads of state and other notables. Catherine de Medici was an avid collector of chalk portraits; drawings exist with the sitter's identity penned in her own hand in the margin. I can imagine Catherine, ever the skilled diplomat, pouring over these portraits in the privacy of her cabinet, memorizing names and faces so as to be able to identify the countless courtiers who flocked around her and her sons. On a less utilitarian note, the portraits became part of a courtly game: groups of courtiers would sit in a circle, cover the name and motto of the sitter written on a portrait, and try to identify the man or woman by looks alone.
Thus, portraiture and celebrity fed off each other: the noteworthy person (famous by virtue of his station, family, fortune or accomplishments) would strive to have his portrait drawn; the very fact that a person managed to obtain a portrait endowed him with a certain measure of notoriety. As E. Jollet points out in his excellent book Jean et François Clouet (1998), there were definite social stakes in gaining access to portraiture; having one's portrait done valorized the sitter, especially in the context of the court.
What strikes me about the Clouet portraits is the amazing detail and lifelikeness of the depictions. Think how amazing, in an era that did not yet know the wonders of photography, the skill of the portraitist to draw close likenesses must have seemed. I myself am grateful to the Clouets and their imitators for the documentary value of the surviving portraits. It is so much fun to view their work and discover what the individuals I read about in literature texts and history books actually looked like. If you go here, you can view over 200 of Jean Clouet's works, with the sitters identified when possible. It's an amazing pictorial "Who's Who" of François I's court.