Kaysar Ridha was a houseguest on Big Brother 6 and then returned to the house in Big Brother All Stars. In both seasons Kaysar placed tenth.
His secret partner in the Big Brother 6 House was Michael Donnellan. Kaysar is best known for being the leader of the Sovereign Six alliance. Kaysar was evicted on Day 33 by a vote of 7 to 1, but after a fan vote, he returned to the game on Day 40 following Sarah Hrejsa's eviction. Ultimately he gave up his HOH to Jennifer Vasquez during an endurance after a made deal, only to find himself betrayed and evicted for a second time in a unanimous 7-0 vote finishing in 10th place.
.He later returned for Big Brother All-Stars, where his alliance dominated for the first 4 weeks, but when Danielle Reyes won Hoh in week 5, his ally Janelle Pierzina was targeted. However, after Janelle won the Power of Veto and used it on herself, Kasyar was made the replacement nominee, and evicted in a 5 to 1 vote, placing 10th once again.
Kaysar was the second House Guest (and first male) to compete for a second time in the same season after being previously evicted since Amy Crews. However, Kaysar is the only previously evicted House Guest to not finish in the jury upon his re-entry, as all other returners eventually made the jury stage or returned during the jury stage.
Kaysar holds the record for the most number of eviction votes received in a single season with 16. He also holds the record for the most votes cast against any player with 21.