Examples... in my country (Dominican Republic) the name chewing gum goes by is
chicle, taken from Chiclets (from Adams).
Colin became a synonym for Machetes (I believe due to the brand name Collins).
All razor blades became Gillete.
When you want to say diapers you say Pampers.
All baby food became Compota, even if it wasn't made out of apples, it was Compota.
Pepsi and Coca-Cola are interchangeable (if you ask for one you could get either)
First it was Atari -- all video game consoles were called that, handheld games (even though they were game & watch games from Nintendo) or Coleco Vision .
Then Nintendo took over when the NES launched and even though Sega wanted to make a dent into it, even sega systems were called Nintendo games. Playstation made the final changeover, after them every console got their name back.
Clorox for all Bleachers
Fab for all laundry detergents
All toothpaste were Colgate (you might see Crest or Aim, but you didn't call them that)
Most thin dolls were called Barbies, etc...
Am I missing any others?