Neil is best-known for his title role in "Doogie Howser, M.D." After "Doogie" ended, Neil got involved in theatre, and performed in several Broadway productions. He recently had a small but memorable cameo in the comedy "Harold & Kumar Go to White Castle," in which he played himself... a "drug and sex addicted" version of himself! He is currently starring in "How I Met Your Mother" as the womanizing Barney.