Ah yes, who can forget Michigan J. Frog's time as mascot for the late WB Network (1995-2006)? I'll spare you having to sit through too many ads of the frog singing the praises of shows only three people actually watched. Instead, here's a bizarre ad featuring MJ singing yet another version of his trademark "Hello My Baby" with altered lyrics. It seems oddly appropriate for tax day...
I recall reading how the WB Network originally wanted to use Bugs Bunny as the mascot for their newly formed TV network but ran into issues with that idea since Bugs had just begun being used as the mascot for Warner's "Family Entertainment" division. I guess it was for the best. Bugs didn't have to resort to trying to get people to watch garbage like Nick Freno: Licensed Teacher.
Over on Wikipedia (WARNING: TAKE THE FOLLOWING WITH A HUGE GRAIN OF SALT!) there is this interesting piece of information: The network's first night of programming on January 11, 1995 began with a debate between Bugs Bunny and Daffy Duck over who the network should select as a mascot. The camera then panned over to Chuck Jones drawing Michigan on an easel. When Jones finished, Michigan leapt from the drawing to formally launch the WB.
If such a clip really exists, hopefully it shows up on YouTube someday.