The two have one of the single most important feuds ever booked, with the Beast Incarnate eventually breaking the Deadman's streak at WrestleMania.
That came in 2014, at WrestleMania 30, still one of the greatest Manias ever put on by the company.
Following on from that, Brock and Taker continued their rivalry, and ahead of their rematch at SummerSlam, the two managed to empty the Raw locker room in one of the craziest brawls in WWE history.
On the July 20, 2015 edition of Raw, Paul Heyman cut an impassioned promo in the ring, telling Undertaker that Brock owned him after his win at Mania.
The gong hit, and Taker appeared in the ring, threatening Brock's advocate. Lesnar's music hit and he sprinted to the ring to go toe-to-toe with his greatest foe.
Such was the enormity of the moment, the commentary team departed their desk, allowing the moment to happen without any voiceover.
The pair traded strikes, and were left in a wrestling match on the ground, until security was called out by Triple H to separate the pair. That did not work.
Brock managed to push security back to get another punch in, as did Taker, and the two were again left trading holds on the mat until the locker room emptied.
The likes of The Ascension, Bo Dallas, Cesaro, Sheamus, Mark Henry, Zack Ryder, Rusev and R-Truth were all in the ring, along with plenty more, attempting to separate the pair.
They split off into two teams, one holding Brock, one holding Undertaker, but Lesnar slipped out of the ring, sprinted to Taker's corner, and landed another blow.
Triple H then insisted that Brock be taken to the back but he again broke free and restarted the melee.
A 'This is Awesome' chant broke out among the fans, and after another scuffle, Brock Lesnar shouted "I'm gonna kill you!" Undertaker barked back, "you're going to have to!"
Legitimately awesome as a moment, and Undertaker would go on to get some small measure of revenge, winning at SummerSlam by referee's stoppage.
The feud would then blow off at Hell In A Cell, when the pair went to war, with Brock emerging victorious in a brutal clash.News Now - Sport News