It was he ... / It was him [duplicate]

Solution 1:

Strictly speaking, proper grammar requires subject pronouns be used when they rename the subject. So the subject pronoun "he" follows the verb "to be" as follows:

• It is he.
• This is she speaking.
• It is we who are responsible for the decision to downsize.
• It was he who messed up everything.

Also, when the word "who" is present and refers to a personal pronoun, such as "he," it takes the verb that agrees with that pronoun.

Correct: It is I who am sorry. (I am)

Incorrect: It is I who is sorry.

Correct: It was he who messed everything up. (he messed)

HOWEVER, in informal English, many people tend to follow "to be" verbs with object pronouns like me, her, them, and him. Many English scholars tolerate this distinction between formal and casual English.

Example: It could have been them.

Technically correct: It could have been they.

Example: It was him who messed everything up.

Technically correct: It was he who messed everything up.

For source material that well establishes this, check the following page on Grammar Book: http://www.grammarbook.com/grammar/pronoun.asp .