Michelangelo Buonarroti, Study for the Porta Pia, 1561. Chalk and ink on paper, 44.2 x 28.1 cm. Casa Buonarroti, Florence.
classicaldrawing:

Michelangelo Buonarroti
Male Nude, Seen from the Rear (recto) 
Black chalk, pen and brown ink
260 x 170 mm
1503-04
James McNeill Whistler, A Dancing Woman in a Pink Rober Seen from the Back, 1888. Charcoal and gouache on paper, 23 x 71.12 cm.
John Singer Sargent, Sketch for the Sphinx and the Chimaera (Rotunda), 1917-21. Charcoal on paper, 62 x 45.5 cm (24 7/16 x 17 15/16 in). Museum of Fine Arts, Boston.
Luca Signorelli (c. 1441-1523), Nude Man From Rear. Black chalk, 41 x 25 cm (16 1/8 x 9 7/8 in). Louvre, Paris.
Raphael Sanzio (1483-1520), A Combat of Nude Men. Red chalk over stylus work, 37.9 x 28.1 cm (14 15/16 x 11 in). Ashmolean Museum, Oxford.
Arch of Janus Framing Temple of Vesta by Michael Graves.
Baccio Bandinelli (1493-1560), Male Nude From Sistine Ceiling. Pen and bistre wash, 40 x 21 cm (15 3/4 x 8 1/4 in). British Museum, London.
Tintoretto (Jacopo Robusti) (1512-1594), Draped Standing Figure. Black chalk, 33.4 x 18 cm (13 1/8 x 7 1/16 in). Uffizi, Florence.
Jacopo Pontormo, Study of Angel for the Annunciation, c. 1527-1528. Black chalk and yellowish brown wash over traces of red chalk, heightened with traces of white, on paper, 15 3/8 x 8 1/2 in. Uffizi, Florence, Italy.