#1: John Cena (Nine losses)

Though critics of John Cena claim that the former WWE Champion wins far too much, that certainly hasn't been the case for Cena when he has appeared at the biggest party of the summer: SummerSlam.
In his 14 appearances at the event, Cena has only won 5 times, meaning he's suffered nine losses against some pretty big stars, including Edge, Batista, Randy Orton, CM Punk (twice!), Daniel Bryan and Brock Lesnar Despite people constantly claiming he never puts over other talents, Cena has actually done an amazing job at helping other talents go over, with Seth Rollins beating him in the 'Winner Takes All' match, and AJ Styles picking up a clean victory over him in 2016.
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Daniel Bryan is another Superstar who has bested Cena at the Summer tradition, as it seems that Big Match John's biggest foe isn't the likes of Brock Lesnar or Kurt Angle, but the event itself.