Girl with a Mandolin (Fanny Tellier) is a 1910 Cubist painting by Pablo Picasso. The artwork was one of Picasso’s early Analytic Cubist creations, through which he aimed to reduce organic forms to geometric shapes. It shows the model Fanny Tellier in the nude, with her hands on a mandolin. Tellier volunteered to model for Picasso but, according to the latter, eventually refused to continue sitting for him after the painting took longer to complete than she had expected. Picasso accordingly left the portrait unfinished, though later suggested that he could have done nothing further to improve it.
Picasso painted Girl with a Mandolin late in the spring of 1910, shortly before leaving Paris for the Catalan town of Cadaqués. It was a response to Woman with a Mandolin, a more abstract treatment of the same theme by his friend Georges Braque, and followed two other works by Picasso under the same title. It has been analysed as a partial move away from naturalism, though comparatively legible and close to the visible form by contrast with later Cubist works, and as an important step in Picasso's movement towards focusing on the study of geometric planes. It has also been interpreted both as a de-eroticised nude and as containing autoerotic implications. The art historian T. J. Clark called it "the most ingenious of Picasso's portraits".