Answer:

STOIC

Answer	Crossword Clue
STOIC	Imperturbable
STOIC	Zeno, for one
STOIC	Follower of Zeno

STOIC	Seemingly indifferent
STOIC	Student of Zeno
STOIC	Stiff-upper-lip type
STOIC	Like Zeno
STOIC	Indifferent to pain
STOIC	Uncomplaining
STOIC	Not easily flapped
STOIC	Poker-faced

STOIC	Unflappable
STOIC	Impassive
STOIC	Marcus Aurelius was one
STOIC	Uninclined to complain
STOIC	Hard to reach, in a way
STOIC	Hardly effusive
STOIC	Zeno, notably
STOIC	Passionless

STOIC	Marcus Aurelius, e.g.
STOIC	Unemotional
STOIC	Detached type
STOIC	Showing no pain
STOIC	Unmoved
STOIC	Hard to move
STOIC	Hard to stir
STOIC	Zeno, e.g.

STOIC	Dispassionate
STOIC	Bite-the-bullet type
STOIC	Devoid of emotion
STOIC	Unemotional to a fault
STOIC	Putting on a poker face
STOIC	Unflinching
STOIC	Uncomplaining in the face of adversity
STOIC	Brutus, philosophically

STOIC	Hardly the screaming type
STOIC	Hardly the emotional type
STOIC	Stone-faced
STOIC	Not very emotional
STOIC	Uncomplaining type