#3 Big Cass

WWE had some big plans for Big Cass after his heel turn and we can be sure that putting a world championship on him was not one among those plans. Even before his heel turn, the 7 footer was featured in the fatal four-way match for the Universal Championship in which he lost.
His push was short lived as he was a victim of an untimely injury as he suffered a torn ACL during a match against his former tag team partner Enzo Amore on the post Summerslam episode of Raw and he hasn't been seen in WWE programming since.
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Irrespective of having the looks and the physique of a Vince McMahon kind of guy, he lacked the charisma of a true champion. Unless he makes an effort to improve this once he returns to in-ring action, it is highly unlikely that he will ever hold a world championship in the WWE.