Question: Who plays lily on how i met your mother?
Disambiguated questions and answers: question: Who plays adult  lily on how i met your mother?
Who plays 11-year old lily on how i met your mother?
Who plays 7-year old  lily on how i met your mother?
answer: Alyson Hannigan
Piper Mackenzie Harris
Francesca Capaldi
Natural Questions answer: Alyson Lee Hannigan (from the Wikipedia article "Alyson Hannigan")