Nickelodeon Logo (1984–2005)

Source: http://mychannellogos.wikia.com.License: All Rights Reserved.

George Lois:

In 1984 I created the Nickelodeon logo, which, like a kid's imagination, could be a zillion and one different versions: a bomb, a guitar, an egg, a turkey, or a smile. From that day, the only way you could tell a real Nick logo from an imposter is: the shape is always orange!

Wikipedia contradicts this account, giving credit to Tom Corey and Scott Nash:

Fred/Alan (now Frederator Studios), teamed up with Tom Corey and Scott Nash of the advertising firm Corey McPherson Nash to replace the "Pinball" logo with an "orange splat" logo featuring the "Nickelodeon" name written in the Balloon font, which would be used in hundreds of different variations over the next 25 years.

Fred Siebert (designer of the MTV logo) of Fred/Alan tells his story of the logo creation in detail:

Tom and Scott argued that orange generally clashed with everything and that would make the logo stand out (as long as we didn't let designers try and make it work "correctly.") The splat could morph into any image we liked.

Bob and Gerry didn't buy it. No one else there did either. "It doesn't match anything." "It's flat." "It's not as cool as the MTV logo, what happened to you guys?"

Ultimately, we prevailed. I'm not really sure how, since all their objections were right on. But we were the "logo guys," so they eventually bought our action. I'm thrilled they did, since our work with Nickelodeon is some of my favorite stuff in our careers.

Source: http://mychannellogos.wikia.com.License: All Rights Reserved.

Source: http://mychannellogos.wikia.com.License: All Rights Reserved.

Source: http://www.georgelois.com.License: All Rights Reserved.