Not exactly the Swamp-thing that everyone is familiar with, but instead his first appearance in House of Secrets #92.
I have no idea why someone would write a story that goes from first person naration, to second person naration, to inner-monologue of thrid person characters to the second person narator...Who does that?
I'll tell you who does that -
Writer, Len Wein
Artist, Bernie Wrightson