I will be deciding this through polls. I will only be taking official US seasons into account, so no Canadian seasons or OTT or Celebrity seasons. This is part 1 of the qualifying round, vote for the biggest villain of each season. The top 2 from each season will advance to the next round. Since Big Brother 21 isn't over yet, this poll will only take into consideration seasons 1 through 20. Although, I may put up a poll for BB21 just for fun down the line.
