Troll potter based in Ankh-Morpork.
During Feet of Clay his stores were robbed for clay. He didn't report the robbery at first, because "Wasps don't complain much when they get stung."
It's possible he is a member of the Breccia, since he was a maker of conveniently hollow statues that hid Slab. a side-note from the relevant Yearbook says that the suspicions of the Watch were first aroused when Chalky registered a company called Hollow Statue Imports, which suggests he hasn't quite mastered sublety or discretion.