As everyone knows, The Munsters ran for 2 seasons (1964-6) on CBS. What you don't know is that two of the five leads had to be recast.
Not much is known about Happy Derman, other than the fact that he probably wasn't heard from again after failing to click as Eddie, playing the role with the attitude of a juvenile delinquent and more of a werewolf stereotype, the latter of which was downplayed when Butch Patrick was cast for the final pilot. Joan Marshall (Phoebe) just didn't fit in. When the role was recast, the character was renamed Lily. We cannot be certain if this was simply the same character, having been rechristened. You'll notice, too, that the makeup for Herman (Fred Gwynne, ex-Car 54, Where Are You?) is a tad different. You might say that Herman, ah, bulked up by the time the series actually began.
And who had heard of a laugh track during opening credits, anyway?
Here's the, ah, "rough draft" of "My Fair Munster":
Unfortunately, this is all we have.