The first Power of Veto competition
It's hard to imagine a time in Big Brother history where the coveted Power of Veto wasn't up for grabs, but the shiny token of safety wasn't introduced to the game until Season 3.
Initially, Houseguests competed for the then-silver Power of Veto, which only granted them with the power to remove someone else from the block. It wasn't until the end of the season that the POV turned gold and allowed each week's winner to remove him or herself from the block, too.
To see the first POV in action, watch Big Brother Season 3 on CBS All Access.