Lisa Dean Ryan (born April 30, 1972) is an American actress.
 She played Wanda Plenn, the girlfriend of the eponymous character in the series "Doogie Howser, M.D.", appearing in the series from 1989 to 1992.
James Barrie Sikking (born March 5, 1934), credited as James or James B. Sikking, is an American actor known for his role as Lt. Howard Hunter on the 1980s NBC TV series "Hill Street Blues".
 He also starred on the ABC TV series "Doogie Howser, M.D." as Dr. David Howser and on the short-lived 1997 CBS drama series "Brooklyn South" as Captain Stan Jonas.
 All three series were co-created by Steven Bochco.
 Sikking did the voice of General Gordon on the short-lived 1998 cartoon series "Invasion America".
Max Casella (born Maximilian Deitch; June 6, 1967) is an American actor.
 He is known for his roles on the television series "The Sopranos", "Boardwalk Empire", "Doogie Howser, M.D.", "Vinyl", "Cro" and the voice of Daxter in the "Jak and Daxter" video game series.
David Lee Stenstrom (a.k.a. David Stentstrom) (born November 10, 1953) is an American actor.
 He has appeared in various shows, the best known of those roles perhaps being his work with Saban, which includes being the voice of King Mondo in "Power Rangers Zeo" and Hal Stewart in "Masked Rider".
 Stenstrom has also made guest appearances on many television shows throughout his career, including "General Hospital", "Doogie Howser, M.D.", "Full House" and "Murder, She Wrote".
 He was also known for his role as Waldo the inventor on the Nickelodeon show, "Out of Control".
Markus Redmond (born February 5, 1971) is an American actor.
 He is best known for his role as Raymond Alexander, in the comedy-drama series "Doogie Howser, M.D.", co-created by Steven Bochco.
 Redmond joined the cast at the start of the show's second season in 1990 until the series ended in 1993.
 He worked with Bochco again on two other series, in recurring roles as P.O. Lucas on "NYPD Blue" and as Mark Washington in "Murder One".
Stephen Cragg is an American television producer and director.
 Cragg has directed several network television series.
 Cragg also directed episodes of "ER, Boston Legal, Detroit 1-8-7, Southland, Harry's Law, Northern Exposure, Doogie Howser, M.D." and "Third Watch".
 Cragg was also a producer on "A Year In The Life" (for which he received the Best Miniseries Emmy), "Doogie Howser, M.D.", "The American Embassy" and "The Byrds of Paradise".
Lawrence Pressman (born July 10, 1939) is an American actor, probably best known for roles on "Doogie Howser, M.D.", "Ladies' Man", a recurring role on "Profiler", the title character on "Mulligan's Stew" and as a fictional scientist in the 1971 film "The Hellstrom Chronicle".
Neil Patrick Harris (born June 15, 1973) is an American actor, comedian, magician, and singer, known primarily for his comedy roles on television and his dramatic and musical stage roles.
 On television, he is known for playing the title character on "Doogie Howser, M.D." (1989–1993), Barney Stinson on "How I Met Your Mother" (2005–2014, for which he was nominated for four Emmy Awards), and Count Olaf on "A Series of Unfortunate Events" (2017 onward).
Rif Hutton (born November 28, 1962) is an American actor.
 He is perhaps best known for his recurring role as Dr. John Welch in the comedy-drama series "Doogie Howser, M.D.", appearing in that series from 1990 up to its conclusion in 1993.
 From 1997 to 2001, he appeared in a recurring role as Lt. Cmdr. Alan Mattoni on the series "JAG".
 Hutton is also notable for playing Russ Beeler, a fictional owner of a KFC establishment, appearing in a number of KFC commercials in the early to mid 1990s.
Philipp Moog (born August 29, 1961 in Munich, Germany) is a German television actor, author and voice actor.
 He is the German voice of Neil Patrick Harris, Ewan McGregor and Owen Wilson.

Question: Which actor portrays the German voice of the American actor who played the title character on "Doogie Howser, M.D.?"
Answer: Philipp Moog