Alyson Lee Hannigan is an American actress. She is known for her roles as Willow Rosenberg

Willow Rosenberg

Willow Rosenberg is a fictional character created for the fantasy television series Buffy the Vampire Slayer . She was developed by Joss Whedon and portrayed throughout the TV series by Alyson Hannigan...

 in the cult classic television series Buffy the Vampire Slayer, Michelle Flaherty in three American Pie films, and Lily Aldrin

Lily Aldrin

Lillian "Lily" Aldrin is a fictional character created by Carter Bays and Craig Thomas for the CBS television series How I Met Your Mother, portrayed by American actress Alyson Hannigan. She is the wife of Marshall Eriksen and the best friend of Robin Scherbatsky...

 on the CBS

CBS

CBS Broadcasting Inc. is a major US commercial broadcasting television network, which started as a radio network. The name is derived from the initials of the network's former name, Columbia Broadcasting System. The network is sometimes referred to as the "Eye Network" in reference to the shape of...

 sitcom How I Met Your Mother

How I Met Your Mother

How I Met Your Mother is an American sitcom that premiered on CBS on September 19, 2005, created by Craig Thomas and Carter Bays.As a framing device, the main character, Ted Mosby with narration by Bob Saget, in the year 2030 recounts to his son and daughter the events that led to his meeting...

.
Hannigan was born in Washington, D.C.

Washington, D.C.

Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....

 She is the only child of Emilie Posner, a real estate agent

Real estate broker

A real estate broker, real estate agent or realtor is a party who acts as an intermediary between sellers and buyers of real estate/real property and attempts to find sellers who wish to sell and buyers who wish to buy...

, and Al Hannigan, a truck driver. Hannigan is of Irish

Irish American

Irish Americans are citizens of the United States who can trace their ancestry to Ireland. A total of 36,278,332 Americans—estimated at 11.9% of the total population—reported Irish ancestry in the 2008 American Community Survey conducted by the U.S. Census Bureau...

 descent on her father's side and Jewish on her mother's.