头目 refers to a leader or chieftain, often with a connotation of leading a group outside of formal authority, such as a bandit chief or pirate leader. It carries a slightly informal or historical tone compared to neutral words like 领导.
那个海盗头目被警方抓住了。
nàge hǎidào tóumù bèi jǐngfāng zhuā zhù le.
That pirate leader was caught by the police.
小说里的土匪头目其实是个好人。
xiǎoshuō lǐ de tǔfěi tóumù qíshí shì gè hǎo rén.
The bandit leader in the novel is actually a good person.
他是这伙人的头目,所有人都听他的。
tā shì zhè huǒ rén de tóumù, suǒyǒu rén dōu tīng tā de.
He is the leader of this group; everyone listens to him.