|Although most grammarians still maintain the distinction between nominative who and objective whom, conversational use is blurring the lines and whom is disappearing from informal writing.
Some style experts now consider the use of who for whom proper idiomatic English. Even so, it is best to follow traditional who/whom usage in most writing.
Strict: Whom should I call?
Informal: Who should I call?
Correct: To whom should I give the prize?
Correct: Give the prize to whoever calls first.
(Whoever is correct because it is the subject of calls;
the entire phrase whoever calls first is the object of the preposition to.)
Lowercase who and whom in all references including the Deity or Jesus.
Generally avoid using with animals.
See also: ANIMALS.