Brock Lesnar was cited by Critical Bench as having benched 475 lbs. as of 2015, purportedly the maximum amount of weight he was capable of benching safely. This number is subject to change based on Lesnar's workout routine, aging process and other factors which must be accounted for.
Lesnar is known for not indulging in power-lifting. Power-lifting is a discipline which focuses on the ability to lift as an end unto itself and ignores the cultivation of balanced and useful muscle groups.
Lesnar does not lift significantly more than much smaller men than himself who do pursue power lifting. His strength has traditionally been cultivated for performance in the ring.