For quantity:
* Few: This is the most common and general antonym.
* Little: Used for uncountable nouns.
* Some: Indicates a small or indefinite number, but more than none.
* None: Indicates a complete absence of something.
For variety:
* Few: Can also be used to indicate a limited variety of something.
* Single: Indicates only one of something.
* Unique: Indicates something that is one of a kind.
For emphasis:
* No: A strong negation of "many."
* Not many: A weaker negation of "many."
Example:
* Many people attended the concert. (Antonym: Few people attended the concert.)
* There are many different types of flowers. (Antonym: There are few different types of flowers.)
* We have many problems to solve. (Antonym: We have no problems to solve.)
Choose the best antonym based on the specific meaning of "many" in your sentence.