John Nielsen is an American actor and producer best known for his role as Dave Watt in The Secret World of Alex Mack.


Nielsen was born on October 17, 1958, in New York City, New York, and raised in the city's Brooklyn borough. His family was comprised mostly of police officers and firefighters. As an adult, he studied aeronautical engineering at Embry-Riddle Aeronautical University in Daytona Beach, Florida. After working at the Brooklyn Navy Yard as a shipfitter for many years, Nielsen attended Herbert H. Lehman College in the Bronx borough. It was where he discovered acting, which he became interested in. He then spent a few years doing regional theater in Seattle, Washington, before moving to Los Angeles, California, in 1989. He starred in several commercials, TV guest-star roles, and small film parts before being cast as a series regular on the Nickelodeon-produced series The Secret World Of Alex Mack.

On Criminal MindsEdit

Nielsen portrayed Dennis Cutler, who was murdered by a serial killer and arsonist alongside the rest of his family in the Season Two episode Ashes and Dust.


  • Eternity Hill (2015) as Major Jack Knicks
  • Deep Dark (2015) as Uncle Felix
  • Cracked (2015) as Uncle John (short)
  • The Blacklist (2014) as Paul Wyatt
  • Jersey Boys (2014) as Record Executive (uncredited)
  • Meddling Mom (2013) as Kent Burns
  • Rizzoli & Isles (2012) as Michael Lawson
  • Sweet Old World (2012) as Brian Hinkle
  • Hereafter (2010) as Factory Supervisor
  • Case 219 (2010) as Det. Henry
  • Kings (2009) as Judah Shepherd
  • Transformers: Revenge of the Fallen (2009) as USS Roosevelt Captain
  • Rails & Ties (2007) as Dr. Offenberger
  • Criminal Minds - Ashes and Dust (2007) TV episode - Dennis Cutler
  • Pandemic (2007) as TV News Producer
  • Ghost Whisperer (2006) as Andy Rieser
  • Flags of Our Fathers (2006) as Senator Boyd
  • Heist (2006) as Vic
  • Gone But Not Forgotten (2005) as Merrill (credited as John Nielson)
  • Las Vegas (2005) as Prosecutor
  • NYPD 2069 (2004) as Westin
  • Third Watch (2004) as Mr. Hayden
  • 24 (2004) as First Reporter
  • The Division (2003) as Bob McDonald
  • NYPD Blue (2001-2003) as Det. Ed Markinson/Officer Palmer/Agent Dwyer (3 episodes)
  • Judging Amy (2002) as Doctor
  • The Dogwalker (2002) as Dave
  • Race to Space (2001) as Science Reporter (credited as John Neilsen)
  • Scenes of the Crime (2001) as Player #1
  • Double Bang (2001) as Young Man
  • End of Days (1999) as Hospital Cop (credited as John Nielson)
  • P.U.N.K.S. (1999) as Lobby Security Guard (video)
  • Whatever It Takes (1998) as Walker
  • Ground Control (1998) as Pissed Off Pilot
  • True Friends (1998) as Cop
  • The Secret World of Alex Mack (1994-1998) as Dave Watt (24 episodes)
  • Mitzi & Joe (1997) as Johnny
  • Goldilocks and the Three Bears (1995) as Carswell
  • Raging Angels (1995) as Band Manager (uncredited)
  • The Can (1994) as Mr. Coke
  • Live Wire (1992) as Richard
  • Knots Landing (1991) as Reporter


  • Egg (2001) - Co-Producer (short)


For an up-to-date filmography, see here.

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