The cases of pronouns are used differently in sentences.
|I||we||me||us||my, mine||our, ours|
|you||you||you||you||your, yours||your, yours|
|he, she, it||they||him, her, it||them||his, her, hers, its||their, theirs|
Definition: Subject pronouns (also called nominative pronouns) are used as the subjects of sentences or as subject complements following linking verbs.
I bit the monster ... You bit the monster ... He bit the monster ... She bit the monster ... It bit the monster ... We bit the monster ... They bit the monster.
The superhero was . (linking verb)
The superhero was I ... The superhero was you ... The superhero was he ... The superhero was she ... The superhero was it ... The superheroes were we ... The superheroes were they. (Linking verbs work backwards as well - I was the superhero.)
Note: In informal speech, it is now acceptable to say things like "It's me" instead of "It is I," even though it is not technically grammatically correct.
Definition: Object pronouns (also called objective pronouns) are used as direct objects, indirect objects, or objects of prepositions.
The monster bit me ... The monster bit you ... The monster bit him ... The monster bit her ... The monster bit it ... The monster bit us ... The monster bit them.
Definition: Possessive pronouns show ownership.