御兄さん[oniisan] older brother
御兄ちゃん[oniichan] familiar form of "older brother"
御兄弟[gokyoudai] siblings
家兄[kakei] (my) elder brother
雅兄[gakei] polite word in letter to friend

義兄[gikei] brother-in-law
兄さん[niisan] older brother
兄嫁[aniyome] elder brother's wife
兄貴[aniki] one's senior