The noun or pronoun that the sentence is about; the doer of the action
Predicate noun
The noun that describes or identifies the subject
Nominative of address or vocative
The noun is being addressed directly
Nominative absolute
The noun is being described or modified by a participle which has no grammatical connection with any part of the sentence, but expresses an idea related to the verb
Exclamatory nominative
The noun that does the work of an interjection to express sudden or strong feeling
Appositive
The noun that describes or identifies another noun in the subjective case; usually enclosed in comma/s but not in all sentences