Played by Alyson Hannigan and born in 1978, is a kindergarten teacher. She is married to Marshall Eriksen and grew up in Brooklyn, New York. Lily also dreams of being an artist and at one point paints a portrait of Marshall in the nude. She also has a huge debt problem because of her impulsive buying practices. She is able to hide this from Marshall until they apply for a mortgage. She cannot keep a secret, and is often shown to be the most selfish and spoiled of the group, but despite those traits she is a very caring person and will much of the time do thankless acts for the good of her friends. She met Marshall and Ted in college and almost immediately started dating Marshall.
They were together for about 9 years and engaged for almost a year when Lily broke up with Marshall to move to San Francisco to concentrate on her art. She was there for a summer and came back to NYC but Marshall was too hurt that they stayed separated for another couple months afterward. They eventually patched things up and got married. They moved into an apartment in Dowisetrepla which they do not know at first stands for Down Wind of the Sewage Treatment Plant.
They want children, but for a while are scared so they don't try. Later Lily and Marshall make a bet that once they have seen the doppelganger of every member of their gang they will start trying for a child. By the summer of 2010 they have seen all but Barney's doppelganger when Lily sees what she thinks his doppelganger (it wasn't). The rest of the gang knew this meant she was ready for a child and let her believe it.
--Gurpreet--