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

mazologist (s) (noun), mazologists (pl)
Someone who studies the animal class of Mammalia which refers to warm-blooded creatures that have body hair and feed milk to its young.
mazomantist (s) (noun), mazomantists (pl)
Someone who predicts the future while watching a baby nursing milk from his or her mother.
An opium eater or one who eats opium.
A person of mediocre talents or ability; sometimes a person who takes a middle course.
megistothermic, megistotherm, megistothermy
A plant requiring a very high temperature for growth.
meliorist, melioristic
A disputant who advocates reform with the belief that human society can improve and that people can aid in making it better for everyone.
memophilist (s) (noun), memophilists (pl)
A person who loves and collects bookmarks: As a memophilist, Judy had a wide variety of bookmarks from various bookstores in different cities, and some of them were made of leather, some were plastic, and some were made of metal.
Someone who has a strong or spellbinding appeal; a fascinating person.

When the members of an audience sit mesmerized by a speaker, their reactions do not take the form of dancing, sleeping, or falling into convulsions; however, if Franz Anton Mesmer were addressing the audience, such behavior could be expected.

Mesmer was a visionary 18th-century physician who believed cures could be effected by having patients do things such as sit with their feet in a fountain of magnetized water while holding cables attached to magnetized trees. Mesmer then came to believe that magnetic powers resided in himself, and during highly fashionable curative sessions in Paris he caused his patients to have reactions ranging from sleeping or dancing to convulsions.

These reactions were actually brought about by hypnotic powers that Mesmer was unaware of possessing. One of his pupils, named Puységur, then used the term mesmerism (first recorded in English in 1802) for Mesmer's practices. The related word mesmerize (first recorded in English in 1829), having shed its reference to the hypnotic doctor, lives on in the sense “to enthrall”.

—From information found in
The American Heritage® Dictionary of the English Language
metartephilist (s) (noun), metartephilists (pl)
A collector of metalwork: Clive had a lot of antique objects made of metal, and, as a metartephilists, had them on display at the local museum.
metempsychosist (s) (noun), metempsychosists (pl)
Someone who believes that it is posible for psychic actions to take place from one mind to other minds.
One versed in the study of meteors.
Methodist (s) (noun), Methodists (pl)
1. A member of an evangelical Protestant church founded on the principles of John and Charles Wesley in England in the early 18th century and characterized by active concern with social welfare and public morals: "Originally, the word Methodist applied to members of a society founded at Oxford, from the methodical habits of life and worship it promoted.
2. Uncapitalized: Someone who emphasizes or insists on systematic procedures.
Someone who is versed in or who is a specialist in metoposcopy or the interpretation of facial wrinkles, especially those on the forehead, to determine the character of a person.
miasmatist (s) (noun), miasmatists (pl)
1. Someone who has made a special study of diseases arising from miasmata or miasmas.
2. Those who are versed in the phenomena and nature of noxious exhalations.