One of my favorite characters on the show was that guy who played "Roy Trendell" (although he was often "Mr. Wheeler").
I don't know the actor's name, but I've seen him on many shows and he was just dynamite on "Green Acres." It's a pity they didn't show him more. He was this big, intimidating, unpleasant, belligerent farmer who was probably Mr. Douglas' most vocifeous enemy in Hooterville.
One of my favorite bits was when he was Wheeler and Eb was dating his daughter, Darlene. Eb brings along Oliver and Lisa as his "parents" to meet The Wheelers. It was hilarious! One bit of dialogue went something like this:

WHEELER: You want a drink, Douglas?
DOUGLAS: Yes, I'd love a drink.
WHEELER: Sorry, we're teetotallers, we don't keep alcohol in the house.
DOUGLAS: Then why did you ask me...?
WHEELER: You like to drink during dinner?
DOUGLAS: Yes.
WHEELER: You ever drink before dinner.
DOUGLAS: Yes, I...
WHEELER: How about AFTER dinner?
DOUGLAS: Mmm, well...
WHEELER: You drink pretty good. You ever consider AA?