#4 Anyone but you, Roman
Braun Strowman debuted as a member of the Wyatt Family to help thwart Roman Reigns in 2015, who was at odds with Bray Wyatt. The two had a long and intense feud during the summer and fall, with the likes of Strowman, Dean Ambrose, and Luke Harper in the background of their battles. However, their history dates back to the start of 2014.
Wyatt and Reigns initially did battle in WWE as part of their respective factions. The Shield shared some classic wars with the Wyatt Family, most notably at the Elimination Chamber pay-per-view. The 'Eater of Worlds' won that battle, but it was the Big Dog who emerged victorious in 2015.
Their feud culminated with a solid Hell in a Cell Match. Roman Reigns emerged victorious, prospectively making him a likely target of Wyatt.
Bray Wyatt's monstrous alter-ego first met the Big Dog when he got speared at SummerSlam.
They are now the two biggest stars on SmackDown, with the basis for an extended feud between the pair likely coming from 2015. Roman Reigns eventually had his own program against Wyatt's star follower. One that was definitely more brutal, one that made the Monster who he is.