VIDEO: Nathan Fillion Visits Neil Patrick Harris' 'PUPPET DREAMS'

On the next episode of Neil Patrick Harris' NEIL'S PUPPET DREAMS, Neil's unique physiology causes a stir in the puppet medical community. Harris' Dr. Horrible co-star, actor Nathan Fillion makes a guest appearance on the show. Get a sneak peek below!

Neil's Puppet Dreams debuted in November and airs every Tuesday except Christmas and New Year's Day on the Nerdist YouTube Channel. Each episode of the seven-part Web series presents an exclusive look at Harris' puppet-infested dreams. Nathan Fillion and Joe Manganiello guest star.

"The concept of dreams seemed like a great way to tell all kinds of different stories in all kinds of different styles," Harris, 39, said in a telephone interview with USA Today. "You can dream and your dreams can be hilarious, your dreams can be terrifying, your dreams can be poignant, or your dreams can be absolute nonsense."

Harris made his Broadway debut opposite Anne Heche in the Pulitzer-Prize winning drama, Proof. Subsequently, Harris also starred on Broadway as the Emcee in Cabaret, and as The Balladeer/Lee Harvey Oswald in the Tony Award-winning production of Assassins. His additional theatrical credits include roles in All My Sons, Tick, Tick...Boom, The Paris Letter, Sweeney Todd, Rent, and Romeo and Juliet. Harris made his theatrical directorial debut with I Am Grock at the El Portal Theatre in North Hollywood, and he recently helmed a production of Jonathan Larson's Rent at the Hollywood Bowl in Los Angeles. He has also served as host of the Tony Awards Ceremony.

On screen, Neil has starred in numerous feature films, including Beastly, Cats & Dogs 2: The Revenge of Kitty Galore, Cloudy with a Chance of Meatballs, Harold and Kumar Escape from Guantanamo Bay, Harold and Kumar Go to White Castle, Undercover Brother, The Next Best Thing, The Proposition, Starship Troopers, and Clara's Heart (Golden Globe nom.) The Best & the Brightest; The Smurfs; and the third installment in the Harold and Kumar film series, A Very Harold and Kumar Christmas.

On television, Harris gained notoriety as the beloved title character in "Doogie Howser, M.D." (People's Choice Award, Golden Globe nom.), as well as the lead in the NBC comedy series, "Stark Raving Mad." Along with guest-starring roles in "Glee" (Emmy Award), "Numb3rs," "Law & Order: Criminal Intent," "Will & Grace," and "Boomtown," Harris has also starred in several made-for-television movies, including "Yes, Virginia," "The Christmas Blessing," and "The Wedding Dress."