Someone who flies a balloon.

Roget 269: sailor, mariner, navigator; seaman, seafarer, seafaring man; dock walloper [Slang]; tar, jack tar, salt, able seaman, A.    B.; man-of-war's man, bluejacket, galiongee^†, galionji^†, marine, jolly, midshipman, middy; skipper; shipman^†, boatman, ferryman, waterman^†, lighterman^†, bargeman, longshoreman; bargee^†, gondolier; oar, oarsman; rower; boatswain, cockswain^†; coxswain; steersman, pilot; crew.    aerial navigator, aeronaut, balloonist, Icarus; aeroplanist^†, airman, aviator, birdman, man-bird, wizard of the air, aviatrix, flier, pilot, test pilot, glider pilot, bush pilot, navigator, flight attendant, steward, stewardess, crew; astronaut, cosmonaut; parachutist, paratrooper.    ... show more

Dutch: ballonvaarder
Polish: baloniarz