How I Met Your Mother has introduced us to the mother. This reveal took place to close out Season 8, as seen here.
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Will we finally meet her? Watch this promo now for the How I Met Your Mother season finale.
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How I Met Your Mother Season 8 Episode 24 Quotes

Robin: A week from today we are going to be legend, wait for it...
Barney: Married!

I would open a vein in my arm if I could bleed that locket out, just to make her happy.

Ted