Informal:
* Party animal: This is the most common and straightforward term.
* Life of the party: This emphasizes their outgoing and entertaining nature.
* Social butterfly: This highlights their ability to connect with many people.
* Night owl: This emphasizes their preference for staying up late.
* Reveller: This term has a slightly more old-fashioned feel.
* Partygoer: This is a more neutral term, simply meaning someone who enjoys parties.
* Fun-loving: This emphasizes their enjoyment of having a good time.
More negative connotations:
* Party pooper: This is the opposite of a party animal, someone who spoils the fun.
* Wild child: This suggests a somewhat reckless and out-of-control personality.
* Heavy drinker: This focuses on their alcohol consumption.
* Womanizer/Playboy: These terms imply a focus on romantic relationships and casual encounters.
The best term to use will depend on the context and the specific type of party animal you are describing.