W5 may refer to:

• W5, a form used by the United States Internal Revenue Service for filing Earned Income Credit information.
• W5, aka IC 1848, a large star-forming region in Cassiopeia lying about 7,000 light years away.
• W5 nuclear warhead, another name for the Mark 5 nuclear bomb.
• London W5, a London postal district.

• W-FIVE, a Canadian television news program.

• The Five Ws of journalism: Who? What? Where? When? and Why? (and often How?)

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