Harold Charles Sydney Heylen (25 May 1923 – 4 December 1996), credited as Syd Heylen, Sid Heylen and Sydney Heylen, was an Australian character actor (radio, stage, television and film), comedian, and variety performer.
Best known as publican "Cookie" Locke in television serial A Country Practice, he often performed in a traditional vaudeville style in the vein of Roy Rene, and also sang and played banjo and ukulele.
He went into vaudeville after World War II and in 1956 starred in the variety show "The Show of Stars" with Hal Lashwood and John Ewart.
Heylen became well known during the 1960s on television as a regular performer on the HSV-7 variety show Sunnyside Up in Melbourne for 10 years, appearing as "Sydney from Sydney".
He teamed up with other comics, such as Honest John Gilbert, presenting comedy sketches in between the musical items.