1) Blockhead 2) Bull in a china shop 3) Butterfingers 4) Clumsy fellow 5) Clumsy one 6) Clumsy sort 7) Dolt 8) Dropper 9) Dullard 10) Hardly the epitome of grace 11) One often dropping things 12) One who takes a lot of trips 13) One with two left feet 14) Pillock 15) Poor fish 16) Pudden-head 17) Pudding head 1) Boob 2) Bumbler 3) Clatterer 4) Clod 5) Dolt 6) Galoot 7) Lout 8) Lummox 9) Oaf 10) Palooka 11) Shlep 
[English words of Yiddish origin] clumsy person (from Yiddish קלאָץ klots 'wooden beam', cf. German Klotz)
Klutz is American and Canadian slang for a clumsy or stupid person.
a clumsy, awkward person. · a stupid or foolish person; blockhead.