Stomatol! It might not be a household name in the states, but the toothpaste brand is known in Sweden where it is from, due in large part to the historic illuminated sign that has graced the Stockholm skyline for over a century.
While it is easy to see this as a neon sign, the Stomatol sign is actually illuminated by light bulbs, not the more common neon tubes that are used nowadays. Nevertheless it is still animated much like the neon signs seen everywhere today. Shaped like a massive tube of toothpaste, emblazoned with the brand name, when the sign is in action the letters illuminate before other lights in the sign that then create the illusion that toothpaste is being squeezed out onto a brush. Assumedly Stockholmers have really fresh breath.
The sign was first erected in 1909, becoming the first animated sign in the entire country. It then continued to promote its brand name dental product almost continually, all the way to the modern day. There were a couple of times when the sign went without power for a few years, and it has changed location more than once, but it is still a landmark today.
If you are visiting the city, and want to see a bright piece of Stockholm history, go to Klevgränd 1 B and just look up. It's hard to miss a giant tube of toothpaste.