代役(だいやく)substitute (e.g. actor), substitution, stand-in, double

体調不良(たいちょうふりょう)の俳優(はいゆう)の代役(だいやく)を務(つと)めました。

I served as a substitute for the actor who was in poor health.

急遽(きゅうきょ)代役(だいやく)を立(た)てたので、少（syじ）し不安(ふあん)を感(かん)じています。

Since we quickly arranged for a substitute, I feel a little uneasy.

代役(だいやく)のおかげで、無事(ぶじ)に舞台(ぶたい)を成功(せいこう)させることが出来(でき)た。

Thanks to the substitute, we were able to successfully complete the stage performance without any issues.

議長(ぎちょう)の代役(だいやく)をたびたび努(つと)めていた彼女(かのじょ)がついに議長(ぎちょう)になったそうだ。

It seems that she, who frequently served as a substitute for the chairperson, finally became the chairperson.

代役(だいやく)なしで全(すべ)てのアクションシーンをこなすとは…なんて努力家(どりょくか)なんだ！

To perform all the action scenes without a substitute... what a hard worker!