List of idiomas related to people. A list of idioms in alphabetical order can be found following this link Idioms - alphabetical order
• Rotten apple: one bad person who has a bad effect on all others in the group.He ruined the company's reputation. He was a rotten apple
• Loose cannon: an unpredictable person who may cause damage if he/she is not controlled.She sometimes gets out of control.She's a bit of a loose cannon
• Couch potato: a person who lives a sedentary lifestyle, never doing any exercise.He must be the laziest person I've ever met. He's a totalcouch potato
• Wet blanket: a negative person who ruins other people's good times.He complains whenever we try to have fun. He's a bit of a wet blanket
• Big cheese: an important, influential person.She has a lot of power. In that organisation she's a big cheese
• Tough cookie: someone who is strong enough to deal with difficult or violent situations.She broke her arm and still refused to give up. She's a tough cookie