Question: Who played Gary Ewing before the actor that also appeared in "The Young and the Restless"?

Context paragraphs:
Valene Ewing: Valene "Val" Ewing (maiden name Clements, formerly Gibson, Waleska), portrayed by Joan Van Ark, is a fictional character in the CBS primetime soap opera "Knots Landing", a spin-off from the long-running series "Dallas", in which she also appeared.  The character originated on "Dallas" in 1978 as the mother of Lucy Ewing and ex-wife of Gary Ewing (the second son of oil baron Jock and Miss Ellie Ewing).  Van Ark made several guest appearances on "Dallas" before becoming one of the main stars of the spin-off "Knots Landing" in December 1979, though she continued to make small appearances in "Dallas" for the next several years.  Van Ark played Valene in "Knots Landing" for thirteen of its fourteen seasons, which made her one of the show's longest running stars.  The character made her last "Knots Landing" appearance in 1997, when she appeared in the reunion miniseries "".  In 2013, Van Ark reprised her character for the new, updated version of "Dallas".

Ian Paul Cassidy: Ian Paul Cassidy born November 4, 1964 in Harrogate, West Riding of Yorkshire) is an English actor who has appeared mainly in American and Australian productions.  In 2000 he played Cracker Bob in "" and in 2001 he had a starring role in the drama series "The Beast", which was cancelled after five episodes.  Cassidy first came to fame as the host of Australian television show "Kids Company", on Channel 10.  He also appeared in many Shakespeare productions across Australia.  During the 1980s he participated in a number of Australian independent films.  During the first years of the 1990s he appeared in many U.S. films like "For the Boys", "Wind" and "In the Line of Fire", and Dimension Film's Sci-Fi :"".  He has mainly appeared in American television series like "The Pretender", "EZ Streets", "", "Walker, Texas Ranger", "Drake & Josh", "Desperate Housewives", "Numb3rs", "24", "The Pacific", "Monk", "The Bold and the Beautiful", "The Young and the Restless" and numerous others.  He has also appeared in many Video Games for MachineGames, including the highly acclaimed "" as Bobby Bram.

Ted Shackelford: Theodore Tillman "Ted" Shackelford III (born June 23, 1946) is an American actor.  He played Gary Ewing in the CBS television series "Knots Landing" (1979–1993); since 2006, he has appeared in a recurring role on the CBS soap "The Young and the Restless," portraying twin brothers William and Jeffrey Bardwell.

Ken Michelman: Ken Michelman (born May 23, 1956) is an American actor primarily known for his role as Abner Goldstein on the TV series "The White Shadow".  He also played Gary Greenberg, Cindy Brady's love interest on the short-lived "Brady Bunch" spinoff, "The Bradys".

Gary Ewing: Garrison "Gary" Arthur Ewing is a fictional character from the CBS soap opera, "Knots Landing", a spin-off of "Dallas".  The character of Gary Ewing was first played by actor David Ackroyd, in a 2-part "Dallas" episode entitled "Reunion", which broadcast in September 1978.  Gary Ewing was the second son of oil baron Jock Ewing and Miss Ellie Ewing, the father of Lucy Ewing and the ex-husband of Valene Ewing.  Over a year later, the part of Gary Ewing was recast for the spin-off "Knots Landing" with actor Ted Shackelford in the role, and Gary became one of the main stars of the series in December 1979.  Ted Shackelford played Gary Ewing in "Knots Landing" for its entire fourteen seasons (1979–1993), while continuing to make occasional appearances in "Dallas" during that time.  The character of Gary made his last "Knots Landing" appearance in 1997, in the reunion series "".  Shackelford reprised his character for the new, updated version of "Dallas" in 2013.

Tony Hale: Anthony "Tony" Hale (born September 30, 1970) is an American actor and comedian.  He is known for his role in the Fox comedy series "Arrested Development" as the neurotic Buster Bluth.  Since 2012, he has played Gary Walsh on the HBO comedy "Veep", for which he won the 2013 and 2015 Primetime Emmy Award for Outstanding Supporting Actor in a Comedy Series.

Jimmi Harkishin: Jimmi Harkishin (born Rajan Harkinshindas, March 1965) is a French-born British actor best known for his role as shopkeeper Dev Alahan in "Coronation Street", which he has played since November 1999.  He's also been featured in the film "East is East" as well as "Bhaji on the Beach".  He played Gary Dunn in the "Jonathan Creek" episode "Danse Macabre".

Max Walker (actor): Max Walker (born December 30, 1986) is a Canadian actor.  He played Gary "Squib" Furlong on the Canadian television show," 15/Love".

Restless (Carl Perkins song): "Restless" is a 1968 song written by Carl Perkins and released as a single on Columbia Records.  The song was recorded on September 27, 1968, and released as a 45 single, 4-44723, on Columbia, in December, 1968, backed with "11-43", reaching no. 20 on the "Billboard" country chart.  The recording, produced by Bill Denny and Larry Butler, also appeared on the May, 1969 Columbia LP "Carl Perkins' Greatest Hits".  The song also appeared on the 1992 Carl Perkins compilation album "Restless: The Columbia Recordings".  The song became a major hit again in 1991 in a new all-star recording by Mark O'Connor and The New Nashville Cats.  Carl Perkins performed the song on the Kraft Music Hall episode hosted by Johnny Cash on April 16, 1969.

Pamela Rebecca Barnes: Pamela Rebecca Ewing (maiden name Cooper; formerly Barnes) is a fictional character from TNT's primetime soap opera, "Dallas", a continuation of the original series of the same name which aired on CBS from 1978 to 1991.  Rebecca was portrayed by actress Julie Gonzalo, and appeared on the show since its pilot episode, which first aired on June 13, 2012.  A member of the Barnes family, the character originated in two episodes of the original series' season 12 (in which she was 5 years old), and also appeared in the TV reunion movie "" (which is not regarded as canon by the 2012 series).  Pamela Rebecca was named after both her aunt, Pamela Barnes Ewing, and grandmother, Rebecca Barnes Wentworth.

Supporting paragraphs: Gary Ewing Ted Shackelford
Answer: David Ackroyd