-ist

(Greek > Latin: a suffix; one who believes in; one who is engaged in; someone who does something)

trivialist
tropist (s) (noun), tropists (pl)
Someone who deals in tropes.
tympanist, timpanist
Someone who plays the kettledrums and other percussion instruments in an orchestra.
typologist
ultraist
unilateralist
unionist
universalist
urinologist
urologist
utopianist
vacationist
Someone who is on vacation.
vaccinist
1. Someone who is a vaccinator.
2. A supporter, or advocate, of vaccination.
vaccinotherapist
Someone who utilizes vaccines to provide immunity treatment against ailments.
vacuist
One who holds the doctrine that the space between the bodies of the universe, or the molecules and atoms of matter, is a vacuum; opposed to plenist.