A juggler was an entertainer skilled in the manipulation of objects, usually by throwing them in the air and catching them before they hit the ground.
In 2364, on the planet Ligon II, a juggler was present at a banquet held for Lieutenant Natasha Yar. The Ligonian juggler used axes in his performance. (TNG: "Code of Honor")
Lwaxana Troi's Parallax colony holoprogram included a hologram of a juggler. In 2368, she brought Alexander Rozhenko into the program to relax during her visit to the USS Enterprise-D. The juggler referred to his juggling balls as "worlds", and ended up eating them after catching one in his mouth and seeing that it tasted good. (TNG: "Cost Of Living")
In 2371, a juggler was one of the performers celebrating the Bajoran Gratitude Festival on Deep Space 9. (DS9: "Fascination")
Ensign Pablo Baytart, a Starfleet officer aboard the Federation starship USS Voyager, was a skilled juggler and was one of the first featured guests on A Briefing with Neelix, in 2372. In his appearance he juggled a collection of PADDs, hyposprays and phasers. (VOY: "Investigations")