The noun 坏人 (huàirén) means 'bad person' or 'villain.' It is a straightforward compound of 坏 (bad) and 人 (person), commonly used in everyday speech and storytelling. It often appears as the object of verbs or in descriptions of antagonists.
故事里的坏人最后都受到了惩罚。
Gùshì lǐ de huàirén zuìhòu dōu shòudào le chéngfá.
The villains in the story were all punished in the end.
别担心,坏人已经被警察抓住了。
Bié dānxīn, huàirén yǐjīng bèi jǐngchá zhuāzhù le.
Don't worry; the bad guys have already been caught by the police.
小朋友要学会分辨好人和坏人。
Xiǎopéngyǒu yào xuéhuì fēnbiàn hǎorén hé huàirén.
Children should learn to tell good people from bad people.