Indefinite Pronouns

Rule 1: Unlike indefinite determiners, French indefinite pronouns (les pronoms indéfinis) do not accompany a noun; they stand in their own place.

However, just like indefinite determiners, some of them can be variable and agree in number and gender with the thing or person they are referring to (for example, chacun or quelqu’un). The others, such as personne, rien, or quelque chose, are invariable.

Aucun, Aucune

Rule 2: Aucun and aucune are indefinite pronouns that can only be used in the singular. They are accompanied by the negative particle ne and mean "none."

Rule 3: Aucun and aucune are often followed by de to indicate the group in question.

Autre, Autres

Rule 4: Autre can refer to either a person or a thing. It can be used in either plural or singular form, and means "the other" or "the others."

Personne

Rule 5: The indefinite pronoun personne replaces a noun and is used as a subject or an object in a sentence. It’s invariable. Personne is used in negative sentences in combination with the negative particle ne. It has the meaning "nobody/no one" or "anybody/anyone".

Quelque chose, Quelqu’un

Rule 6: Quelqu’un and quelque chose are used as subject and object in affirmative sentences. They are invariable whether male or female.

- quelque chose stands for an unknown thing and is translated as "something" or "anything."

- quelqu’un stands for an unknown person and is translated as "someone", "somebody", "anybody," or "anyone."

Rien

Rule 7: The indefinite pronoun rien replaces a noun and is used as a subject or an object in a sentence. Rien is used in negative sentences in combination with the negative particle ne. It’s translated as "nothing" or "anything."

Chacun, Chacune

Rule 8: Chacun replaces masculine nouns and chacune replaces feminine nouns. They are translated as "each" or "everyone."

Rule 9: Chacun and chacune are often followed by de to emphasize that all in a group are included.

Quelques-uns, Quelques-unes

Rule 10: Quelques-uns/quelques-unes (a few, some) stands for quelques and a noun. It’s used to talk about people or things. It’s always used in the plural and has to agree in gender to the nouns it replaces.

Note that the -s at the end of quelques is pronounced before the following uns or unes.

Tout

Rule 11: Tout as a pronoun designates a totality of things or facts. It is invariable and means "everything."

To learn more about the word tout that is very used in French, visit this grammar point.

Indefinite Pronouns with Adjectives

Rule 12: You can use the indefinite pronouns quelque chose, rien, quelqu’un, personne with adjectives. For that, you need to add de between the pronoun and the adjective.