We've one left downtown, but we've been down to just one for decades now. It was Ultramar until very recently.
Our biggest is, I assume, Costco in Galway.
And my fave, of course, are the local North Atlantic ones - they're just so cheerful. I believe they're also now owned by Irving, but with a commitment to maintain the local branding, similar to previous arrangements with Loblaws (locally Dominion), and Molson/Labatt (locally Dominion, India, Jockey Club, Blackhorse, Blue Star, etc.).
There's also Esso (generally with a Tim's) and, I think only one, Shell (with a Needs Convenience).