While Facebook never ended up with a mascot to represent the company, Sean Parker, a co-founder of Facebook and Napster, wanted to have a hedgehog as the company mascot.
Here’s the story told by early Facebook employee Ezra Callahan:
True story: in the very early days of Facebook, Sean Parker wanted to make Facebook’s mascot a hedgehog. We had early plans to build a local business program around each college on the site (a Yelp-like service similar to what later became Facebook Pages). As part of that, Sean wanted us to send each participating business a little blue stuffed hedgehog. Matt Cohler and I even sourced a couple companies to make them.
Sean actually wanted us to get a real hedgehog for the office. Turns out they aren’t street legal in California, or something, but I guess he found a way to obtain one in Nevada. Fortunately (or unfortunately, depending on your affinity for hedgehogs) Sean couldn’t convince any of us to drive there to get one.
The local business program was shelved mid 2005 (we decided a revenue product wasn’t as important after the Accel financing), and Sean let his dream of the hedgehog go with it.
If I’m not mistaken, a couple employees who live near the facebook campus own a hedgehog today. I won’t name them in case they are, in fact, illegal, but I guess that sorta counts.