I would certainly recommend taking a pillowcase to cover a pillow if there is one or your fleece if there is not. If you are used to the camping pillow and it is light and compact (i.e. you know it will be useful, rather than something you have bought for the journey because it seemed like a good idea) then, yes.
I brought one on both journeys (it went into a small stuff sack and came out at a surprising size - & fluffy). Though many folks don't (a pillow case on existing pillows - or clothe's stuffed in it - works okay) - It's one indulgence that worked for me and didn't take up much more room than a wadded up pillow case. I think it cost me about 10 US dollars.
I brought an airline pillow but gave it away on the way. There were some place with pillows, some without, but I was so tired anyways and could sleep really well regardless. later, when I had easy day and wanted something like a pillow, I just rolled a fleece jacket and it worked fine
i used one of those u-shaped blow up pillows
loved it and will take it again when i go back in september
for my third camino
i recommend taking a large bandanna rather than a pillowcase
it's more versatile
you can use it for a tablecloth, sit-upon, washrag,
towel, sun shade etc etc etc