there are 9 total in legit game, which i would probably call prefirst era to premerera... solesteim has 3 or 4 masks.... and other areas could contain more....
if you really want alot, try posting for a return to atmora dlc or something.... it would probably have tons of dragon priest masks..... and i would probably expect them in hammerfall, nordic parts of cyrodil, highrock and elsewhere....
maybe even summerset isle..... but we know little of it....
I think there are fourteen masks but I can't tell the locations. Sorry :(
there are 10 in total one being a wooden mask and 8 being the regular masks and when you put the 8 on there stands in the Bromjunaar Sanctuary in labyrinthian the 9th mask will appear. you have to put the wooden mask on then you are transported back in time to put the masks on their stands and then take the mask off to go back to the present time. the wooden mask is below the stands next to the note and the thief. oh and once you get the 9th mask take all the masks back. my fav is volsung and krosis. oh and there are 3 places in labyrinthian. shalidor's maze, labyrinthian and Lost Valkygg and here is the link to the dragon priest masks.
There are 3 dragon masks added by dragonborn, each increasing damage dealt by a certain element.
Those are dragon priest masks, and there are 8 of them. Krosis, Morokei, Otar, Nahkriin,
Rahgot, Hevnoraak, Vokun, and Volsung. I don't know where all of them are but the wiki has a page on them, just search dragon priest mask. Also you get a ninth one once you collect all 8.
make your own dragon priest masks
plz make a thread thing i do not know how to make one, lolz XD
There is already a thread for making up your own mask here.