Yes, I remember Unknown Worlds...would always stop by the shop after grabbing some Greek Food on the Danforth with the family. For those who aren't familiar with the area, the store was located in the heart of Toronto's Greek Town.
Never bought any back issues from them as they were always slightly pricier than the other downtown Toronto stores.
Roy, there was a store on Yonge St, slightly North of Eglinton...it was the 2nd Silver Snail location and was in operation for several years, but less than a decade. Not certain if that's the store you're referring to.
Shooting Star...good ol' Jimmy was the owner. After he closed both stores, he moved even further North in Markham and opened another store called Kaos Comics. Very small storefront...if you blink, you'll miss it.