I think I'll let some random samples of Wrightson's work speak for itself.
Most of Wrightson's work was for horror comics. He was a frequent contributor of cover art for DC's line of horror titles.
His most famous work was his collaboration with writer Len Wein on Swamp Thing. It was in the pages of that series that Alec Holland's muck encrusted mockery of a man shambled into Gotham City and Bernie gave us a most decidedly thoroughly modern Caped Crusader that challenged the ground-breaking work of Batman artist Neal Adams and inspired Bat-artists for decades to come.
One of Bernie's more personal projects was his adaption of Frankenstein, a sample which can be seen below.