out of character

out of character  {adv.} or  {adj. phr.}

1. Not in agreement with a person's character or personality; not in the way that a person usually behaves or is expected to behave; not usual; unsuitable; uncharacteristic.

Mary is a nice girl. Her fit of temper was out of character.

2. Not in character; unsuitable for a part or character.

It isn't always out of character for a young actor to play an old man, if he is a good actor.

Contrast: IN CHARACTER.