In How I Met Your Mother Series :
In real life:
Neil Patrick Harris, born June 15, 1973 in Albuquerque (New Mexico), is an American actor, producer, host and singer.

He is best known for his role as a gifted young doctor in Doogie Howser, M.D and womanizer Barney Stinson in How I Met Your Mother.
Age : old.
Attribution - Sources - licenses