You can refer to the person who has captured a person or animal as their captor .
例句
They did not know what their captors planned for them.他们不知道抓他们的人打算拿他们怎么办。
英汉词典释义
n.
捕捉者;捕获者
The hostages were well treated by their captors.那些人质受到劫持者的善待。He cleverly tricked his captors.他巧妙地哄骗了捕捉他的人。The philosophy of them during their worst sufferings impressed even their captors.他们在最困苦时仍处之泰然,连捉住他们的人都深有感触。
英英词典释义
Noun
1. a person who captures and holds people or animals