'Big Brother': Julie Chen's 20 Favorite Moments

Day One

"History was made on July 5, 2000, when the first episode of U.S. Big Brother aired. I had no idea what to expect, but I was excited due to what a success it already was in the Netherlands, where it started, and Germany. But I never imagined it would be on for 20 seasons. Expect the unexpected," Chen wrote for Entertainment Weekly.

Chill Town (Season 2)

"Dr. Will and Mike Boogie were the first Big Brother alliance to give themselves a name. It would just be the first of many alliance names that fans have come to love over the years."

The Choices We Make (Season 3)

"Still considered one of the worst moves in Big Brother history, Marcellas did not use the veto he won to save himself and got sent home!"

Here Come the Exes (Season 4)

"In Big Brother's first big casting twist, eight Houseguests moved in but were shocked to learn that five more were joining — and they were all exes of some of the Houseguests already inside!"

Twins? (Season 5)

"Adria and Natalie revealed to the house that they were actually two different people, much to the dismay of their enemy, Jase!"

Kaysar's journey (Season 6)

"Fan favorite Kaysar got a chance to return to the game when America voted him back in. But in the Pressure Cooker competition, he made a deal with Jennifer to keep him safe, allowing her to become HOH. She then betrayed him that week, and he was evicted again."

Dr. Will's Risky Move (Season 7)

"In his infamous veto meeting speech, Dr. Will told everyone he hated them all, asked to be removed from the game, and promised to throw every comp if they didn't comply. This reverse psychology worked, and Will stayed and made it to the final four."

Dick and Daniele (Season 8)

"Their father-daughter saga had many ups and downs during season 8, but both the Donatos did the impossible by making it to the final two, where Dick ultimately went on to win."

Dan Gheesling's Unanimous win (Season 10)

"Dan cemented himself as one of the greatest Big Brother players when he won season 10 by a unanimous vote. This had never been done before — and hasn't happened since."

Jeff's Big Move (Season 11)

"Jeff shocked the house, especially HOH Chima and Jessie Godderz, when he flipped the game upside down by revealing America had given him the coup d'etat! Jeff was safe, and Jessie went to jury!"

Rachel Rants (Season 12)

"After Rachel won the HOH, she called out Kristen and other Houseguests by warning, 'Floaters, you better grab a life vest!'"

Zingbot (Season 12)

"BB12 was the first time Zingbot appeared in the Big Brother house! His zings have become legendary, and now the roasting robot is a staple and highlight of every season."

Dan's Fake Funeral

"Many call it the greatest game move in BB history. Dan was on his way out the door, but gained sympathy and allies with his 'funeral' and not only ended up staying that week, but he made it to the final two."

The Proposal (Season 16)

"Jeff surprised Jordan when they visted the BB16 house. He proposed in the backyard, and Brett Eldredge sang a song to mark the occasion. Now they are happily married with a son, Lawson, and have another baby on the way!"

Undercover Winner (Season 16)

"In what many call a perfect game, Derrick, a real-life undercover cop, went undercover in the BB house, not telling anyone his true profession, secretly orchestrating game moves from the shadows, and ultimately coming out the winner."

Progressive Casting (Season 17)

"Audrey Middleton was a groundbreaking Houseguest, even though she only placed 14th her season."

Nicole Breaks Ground (Season 18)

"Nicole made history when she won BB18. It was the first time a woman won in the finals by beating a man."

The 2016 Presidential Election (BB: Over the Top)

"For the first time ever, Houseguests were locked away during a presidential election. The Houseguests [who participated in the series' only online season on CBS All Access in 2016] were shocked when they were told that Donald Trump actually beat Hillary Clinton!"

Jessica's Halting Hex (Season 19)

"Jessica won the mysterious Halting Hex in the Den of Temptation. The house knew she possessed some sort of power, but it was finally revealed on eviction night, when she and Cody were on the block, that her Halting Hex had halted the eviction and saved them both."

Omarosa's Epic Comeback (Celebrity Big Brother)

"Omarosa went head-to-head with an emotional Shannon Elizabeth, who was distraught after being put on the block and feeling the target on her back. When Shannon asked Omarosa to leave the room, O replied, "You don't dismiss me. I'm not being dismissed."

Big Brother premieres Wednesday, June 27 at 8 p.m. ET on CBS.