Formal:
* 著名 (zhùmíng) - This is the most common and formal way to say "famous".
* 有名 (yǒumíng) - This also means "famous" but is slightly less formal than "著名".
Informal:
* 红 (hóng) - This literally means "red" but is often used to describe something that is popular or famous, similar to the English phrase "hot".
* 火 (huǒ) - This literally means "fire" but is also used to describe something that is popular or famous, similar to the English phrase "on fire".
Examples:
* 他是一位著名的作家。(Tā shì yī wèi zhùmíng de zuòjiā.) - He is a famous writer.
* 这个城市很有名。(Zhège chéngshì hěn yǒumíng.) - This city is famous.
* 这个歌手现在很红。(Zhège gēshǒu xiànzài hěn hóng.) - This singer is very popular right now.
* 这首歌现在很火。(Zhè shǒu gē xiànzài hěn huǒ.) - This song is very popular right now.
Note: The choice of which word to use will depend on the context and the level of formality.