Clark, 30, a professional football player from San Diego, was voted the winner Wednesday and took home the $500,000 grand prize.
The final jury tally was five to four in Clark's favor over runner-up Crispen.
The 23-year-old lifeguard from Hilton Head, S.C., was voted America's Favorite Houseguest, netting Crispen an additional $25,000 on top of his second place winnings.
The "Big Brother 20" finale also featured a marriage proposal -- contestant Chris 'Swaggy C' Williams got down on one knee for Bayleigh Dayton after the couple was apart from each other for 76 days.
The proposal took place as host Julie Chen was asking each couple from the season about their relationships.
"Sitting at home and watching you tell millions around the world how much you loved me and wanted to be with me forever made me realize that girlfriend wasn't enough," Williams said before asking the big question.
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