Ditto 
Definitely HAR-ee. I tend towards a classical Latin pronunciation almost always. The weird part is, I did that even before I took Latin.
Benny TLEE-lahx
TLEE-lahx-oo
You could also say the tl as cl, like in Tlingit (usually pron. “clinkit”).
I’m with WhyNot on everything except Pieter, which I also pronounced pee-AY-ter.
Bene Tleilax/Tleilaxu : Benn-ay TLAY-lax/ TLAY-lax-oo
This seems like a good place to ask this:
- How do you pronounce Combine Honnete Ober Advancer Mercantile (CHOAM)?
- What the Hell, Michigan does it mean?
I always pronounced Harkonnen like a Finnish name, which it resembles:
HAR kuh nin.
First.
I think my eyes were never sure, or didn’t care if that first “L” was an “L” or an “i.” It came out TEEL-ax and teel-AX-oo in my head. Sometimes it was TILE-ax or tile-AX-oo. Like I said though, my brain mostly brushed past it.
Rhymes with nick-nack paddywack (give the dog a bone).
It’s pronounced “Nigel”.
It’s spelled “Kwisatz Haderach” but it’s pronounced “Throatwarbler Mangrove.”
Best giggle I’ve had in a few days. My inner child thanks you! 
You’re welcome. That’s what I think of every time I think of Dune.
Watch the first Dune in which the author consulted on the film. They pronounced words the way they were meant to be pronounced. The words have a lot of guttural hard sounds in them. I love this about the words in that series.
knick-knack paddywhack