I can imagine lots of languages use expressions (metaphorical -) in order to refer to those persons and things not fitting into a group. What would be the expression in your language?

In Dutch : een vreemde eend in de bijt (a strange duck in the bite, which might be the fishing hook)

 

In Greek:

«Όλοι μαζί κι ο ψωριάρης χώρια» ['oli ma'zi ci o psor'ʝaris 'xorʝa]
lit. "all the guys together, and the mangy apart"

«κι» [ci] is the spelling of the phonetically reduced conj. «και» [ce] --> and, when the next word begins with a vowel

«Ψωριάρης» [psor'ʝaris] (masc.) --> mangy, is the colloquial name for the person infected by scabies, a contagious infestation of the skin caused by a mite. The disease is called «ψώρα» ['psora] (fem.) < Classical fem. noun «ψώρᾱ» psṓrā --> scabies, acariasis < with ω-vocalism from «ψῆν» psên --> to rub, scratch (with obscure etymology). In formal language, the person infected by «ψώρα» is a «ψωράριος» [pso'rarios] (masc.), «ψωράρια» [pso'raria] (fem.).

 

Tagalog: Nabubukod sa lahat. ( exceptional from the rest)

 

Hebrew: גלגל חמישי galgal khamishi, which means being the fifth wheel (of a car).
If it's a third person that joins a [romantic] couple - he "will hold for them the candle".

However these are more for situations in which a person is not needed, not exactly because he doesn't fit.

 

You know, it doesnt really fit into what hes asking.
הוא מתכוון לילדים דחויים וכיוצא בזה.
אין לזה משפט ממש בעברית.
what you said fits for couples stuck with someone.

 

אתה צודק. אבהיר את הדברים למעלה.

 

Moment of enlightment: in hebrew:
עוף מוזר of muzar lit strange bird.
יצור yetzur creature.

 

Interesting thread, but I doubt it we will have a lot of examples

Hungarian --- kakukktojás [kakukk cuckoo tojás egg] --- but it can be only a thing, not a person
Czech --- I don't think there is any special phrase

 

Indeed, I am not referring to someone extra, but to someone special, a queer person in a group, someone who does not fit in...

 

In Japanese, we have several words for it:

仲間外れnakama hazure: (仲間nakama=friend, company; 外れhazure=out of something) lit. out of companies, it can describe not only the very outcast person but the situation the person is left out in
村八分murahachibu: (村mura:town, village; 八分hachibu=eight-tenths) hachibu means "not to go with eight(hachi) customs except for two ones" and is diverted to the meaning to leave someone out. (we usually say murahachibu-nisuru, to stand for the meaning "let someone be an outcast")
異分子ibunshi (異i=different; 分子bunshi=particle, entire meaning is an outsider) this is rarely used in conversation
除け者nokemono (退けnoke=exclude, get rid of; 者:-suffix, the person [doing]) meaning the excluded person[people]