I wasn't able to find out who designed the Disney Channel Logo but it is unlikely that any of its forms were created by just one designer.  The first disney channel Logo (1983-1986) is uninteresting and dull, especially as a logo for a kids station, and its counterpart is only slightly better, with a similar setup and a font that was altered to contain the Disney Logo.  After 1997 the logos began to get better.  The Logo that was used from 1997 to 2002 had a creative feel to it with paint splotches for a head and ears but in 2002 the logo's design changed drastically.  The new design was simple with a modern flair.  When the logo was in use, It would usually be shown in the lower left hand corner of the screen and through special effects a disney channel actor would act as though they were applying the logo to the screen with a magic wand. The Logo didn't change very much for a few years, but in 2014 the designers at disney decided to do a new take on their logo.  The new design puts more focus on the name of the company instead of the mascot.  The gradient in the background helps to give the design some depth.  I personally like the logo that was used from 2002-2014, but this is most likely because I grew up watching the disney channel during these years.  

1983–1986

1986–1997

1997–2002

2002–2014

2010–2014

2014–present