-ast +

(Greek > Latin: a suffix; one who; forms nouns from verbs in -ize; nouns denoting the adherent of a certain doctrine, principle, or custom)

agelast (s) (noun), agelasts (pl)
Someone who does not laugh.
chiliast
Someone who believes in the coming of the millennium (a time of great peace and prosperity) when Christ returns to earth.
enthusiast (s) (noun), enthusiasts (pl)
1. Someone who is very interested or involved in something; especially, somebody with a particular hobby.
2. Etymology: from Greek enthkousiaste, "anyone inspired (by a god)", from enthous.
euthanasiast
Someone who advocates euthanasia.
fantast, phantast
1. Someone who has impractical daydreams.
2. A visionary; a dreamer.
3. Someone who predicts the future.
gymnast
An athlete who performs gymnastics; especially, as a competitive sport.
iconoclastically (adverb)
1. A reference to a person who tries to destroy traditional ideas or institutions: "An iconoclastically destructive attempt to overturn certain beliefs or customs."
2. Related to those who want to do away with religious images or who oppose their use in worship: "There are certain iconoclastically serious efforts by some people to get rid of any images of deities that that could be worshipped."
pleonast
Someone who is addicted to pleonasms.
scholiast (s) (noun), scholiasts (pl)
1. A medieval scholar who wrote commentaries on ancient Greek and Latin texts.
2. One of the ancient commentators who annotated the classical authors.
symposiast
A participant in a symposium (a formal meeting held for the discussion of a subject, during which individual speakers may make presentations).