I am trying to build a LEGO castle MOC and might include a small chapel area. I was wondering if any of you have any advice on how I could build a LEGO bishop or clergy minifigure out of existing LEGO parts (i.e. nothing Custom).

Maybe the New CMF judge as a base figure with the robes. The traditional staff should be easy to make. A pearl gold 4bar ad lightsaber hilt from Ninjago, and the gold CMF pirate hand hook stuck in the top to make a shepards crook. The hat will be the tricky part.

Keeping it quite simple, I think something like one of these could work well for clergy.

I've considered using this piece for a Bishop's hat before (haven't tried it so I am not 100% sure how it will look):

https://www.bricklin...tem.asp?P=64797

I like to use the "2 cape" style that I first saw Bruce N.H. use on Classic-Castle. I used black capes (Harry Potter ones work fine turned star-side inwards) and created Benebrictine monks for my latest MOC: Cloister of St Studmore's Abbey:

If you're not planning to do minifig modification, the closest you can get to a bishop's hat is probably Nute Gunray's hat from Star Wars. It's by no means a perfect fit, since it looks distinctly alien, but it's as close as you can get.

I was thinking Gandalf's torso, paired with a dark bluish gray hood piece.

I was thinking Gandalf's torso, paired with a dark bluish gray hood piece.

That works quite well, I think.

Some Jedi torso from SW might work for a monk clad in brown.

King's torso from King's Carriage Ambush has a sort of cross on a necklace, might be usable with Judge's cape for some rich bishop or something.