αὐτός uses the normal case endings, and has gender.
Decl. 2 1 2 Translation Gender M F N Nom. S. αὐτός αὐτή αὐτό he she it Gen. S. αὐτοῦ αὐτῆς αὐτοῦ his her its Dat. S. αὐτῷ αὐτῇ αὐτῷ to him to her to it Acc. S. αὐτόν αὐτήν αὐτό him her it Nom. P. αὐτοί αὐταί αὐτά they Gen. P. αὐτῶν αὐτῶν αὐτῶν their Dat. P. αὐτοῖς αὐταῖς αὐτοῖς to them Acc. P. αὐτούς αὐτάς αὐτά them αὐτός is a versatile word that has three distinct functions.
First, it can function as the third person personal pronoun (he, she, it, they). This is by far its most common use.
Its gender and number are determined by the noun that it refers back to.
Second, it is an intensifier for the noun it is associated with.
ἐγω αὐτός I myself
αὐτός ὁ Ἰησοῦς Jesus himself
αὐτὸ τὸ δῶρον The gift itself
Third, it can function as an identical adjective, meaning "same".
Mk. 14:39 καὶ πάλιν ἀπελθὼν προσηύξατο τὸν αὐτὸν λόγον εἰπών.
He went away again and prayed the same thing.Lk. 13:31 Ἐν αὐτῇ τῇ ὥρᾳ προσῆλθάν τινες Φαρισαῖοι.
At the same time, some Pharisees came