Favourite Canadian-born artists:
Bobby Curtola: probably best known for songs like Hitchhiker, Fortune Teller, Aladdin, Don't You Sweetheart Me, Hand in Hand With You. I'm not sure if he wrote any of his own music. Sadly, he passed away last year.
Jack Scott: probably one of the most forgotten singer-songwriters out there. He's probably best known for My True Love, Leroy, The Way I Walk, Goodbye Baby, Oh Little One (all of which he wrote in the late 50s or early 60s). (By the way, the song The Way I Walk was recorded by a heavy-metal group called The Kramps (sp?) in the seventies.) I don't know why he isn't better remembered. He wrote so much good music (which I'm listening to right now, by the way) and he also recorded gospel music and did an entire album dedicated to Hank Williams.
The Beau-Marks: also an extremely underrated group (compared to, say, The Diamonds). I heard that they didn't exist as a group for very long, but they did write a handful of songs when they were together. To my knowledge, some of their best-known songs are Clap Your Hands, Billy Billy Went a-Walking, Classmate, The Tender Years, Fulfillment. They wrote all five songs, plus some others.
Bryan Adams (probably the only post-1980 artist whom I can really stomach)