J.W. (Jack) McLaren was born in Edinburgh, Scotland in 1895, the youngest of four children, two brothers and a sister. His father and namesake, John Wilson McLaren was a clothier who died in 1899. His mother, Maggie McLaren (Robertson), moved the family to Toronto's High Park Avenue in 1902.

McLaren fought with the Princess Patricia Canadian Light Infantry in WWI, and entertained troops at Ypres Salient, Vimy Ridge and many other locations on the Western Front with the PPCLI Comedy Company and the 3rd Division Dumbells Comedy Troupe.

McLaren was also a talented artist and writer who enjoyed successful careers as a commercial and editorial illustrator, caricaturist, advertising and promotion executive, and painter throughout much of the 20th century.