Similar word to selfcontrolled:

assured, composed, coolheaded, deliberate, detached, dispassionate, impassive, imperturbable, levelheaded, nonchalant, philosophical, phlegmatic, placid, quiet, relaxed, self-controlled, self-possessed, serene, stolid, together, tranquil, unagitated, unemotional, unexcited, unflappable, unruffled