害群之马

1. • lit. a horse that brings trouble to its herd (idiom)
2. • fig. troublemaker
3. • black sheep
4. • rotten apple

Character by character

• 害(hài)do harm to
• 群(qún)group
• 之(zhī)(possessive particle, literary equivalent of 的 de)
• 马(mǎ)surname Ma