<P> The goal of each main challenge involves a new theme and outcome . Contestants are often asked to design and construct a custom outfit, sometimes incorporating unconventional materials . Other challenges focus on the contestants' ability to present themselves on camera, perform with music, or perform humorously . Some challenges become a tradition across seasons . </P> <Table> Judges on RuPaul's Drag Race <Tr> <Th> Judge </Th> <Th_colspan="9"> Season </Th> </Tr> <Tr> <Th> </Th> <Th> </Th> <Th> </Th> <Th> </Th> <Th> 5 </Th> <Th> 6 </Th> <Th> 7 </Th> <Th> 8 </Th> <Th> 9 </Th> </Tr> <Tr> <Th> RuPaul </Th> <Td_colspan="9"> Main </Td> </Tr> <Tr> <Th> Merle Ginsberg </Th> <Td_colspan="2"> Main </Td> <Td_colspan="4"> </Td> <Td_colspan="1"> Guest </Td> <Td_colspan="2"> </Td> </Tr> <Tr> <Th> Santino Rice </Th> <Td_colspan="6"> Main </Td> <Td_colspan="1"> Guest </Td> <Td_colspan="2"> </Td> </Tr> <Tr> <Th> Michelle Visage </Th> <Td_colspan="2"> </Td> <Td_colspan="7"> Main </Td> </Tr> <Tr> <Th> Billy B </Th> <Td_colspan="2"> </Td> <Td_colspan="2"> Main </Td> <Td_colspan="5"> </Td> </Tr> <Tr> <Th> Ross Mathews </Th> <Td_colspan="3"> </Td> <Td_colspan="1"> Guest </Td> <Td_colspan="2"> </Td> <Td_colspan="3"> Main </Td> </Tr> <Tr> <Th> Carson Kressley </Th> <Td_colspan="6"> </Td> <Td_colspan="3"> Main </Td> </Tr> </Table> <Tr> <Th> Judge </Th> <Th_colspan="9"> Season </Th> </Tr> <Tr> <Th> </Th> <Th> </Th> <Th> </Th> <Th> </Th> <Th> 5 </Th> <Th> 6 </Th> <Th> 7 </Th> <Th> 8 </Th> <Th> 9 </Th> </Tr>

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