>>640There actually aren't a lot of people who exclusively draw them. 異形頭 is the tag of pixiv and is where I pick up most of my art.
Off the top of my head though some artists are:
Au Revoir
https://www.pixiv.net/en/users/6832918Lot's of suits, has set characters they draw a lot.
Ichimaru1010
https://www.pixiv.net/en/users/177209Wide variety of heads. Does a lot of unusual objects, one of my favorites.
Michareel
https://www.pixiv.net/en/users/6597090Not exclusively Object Heads, but I want to drop them because the ones they do have are very surreal and a lot more abstract than most artists.
TV and computer heads are the most common type, probably because they can be more expressive than a lot of things. You also get a lot of art of camera heads and sirens due to the Eiga Dorobo anti-piracy ads