Picasso Harlequin: 1917–1937, which weighs in at more than 300 pages. Pierrots are usually wistful and woebegone, while Harlequins are typically bouncy and mischievous, making this presentation all the more special. Picasso has caught this fellow in a graceful moment of waiting or repose before heading into action, presumably in a circus ring. I just love the dangling foot and the drooping cap, as well as the lovely composition, with the horse's head turned away.
Finally, here are several more Picasso harlequins (which he went on to depict in his cubist period as well).