desperado
n
(pl ~es; US also ~s) (dated 旧) man who commits dangerous, esp criminal, acts without worrying about himself or other people 亡命之徒; 暴徒
the desperadoes who robbed the mail-train 抢劫邮车的亡命徒.
Marine Studio biologists have pointed out that, however intelligent they may be, it is probably a mistake to credit dolphins with any motive of lifesaving.