Walter Alexander Midland Bluebird comes to mind, which has morphed into Stagecoach Bluebird over time, and I believe an image of a bluebird was the crest in Alexander days: way outside my area, so no personal recollections. The Greyhound brand in the States, of course, which was tried (unsuccessfully) here.
Bluebird was another that I recalled but there were two. Alexander (Northern) and Alexander (Midland) both used it so it passed on privatisation to both Stagecoach and GRT (now First) who both have the right to use it.
The Alexander company was split into three in the sixties, so all three companies could probably claim the right to use the Bluebird name. I remember seeing the Bluebird emblem on Northern buses when I was small, but over time, the SBG corporate look took over and the Bluebird gradually disappeared. Midland kept it going for much longer, and Northern re-introduced it in 1989 when they re-branded as Bluebird Northern. After the Stagecoach buyout Northern was legally known as Bluebird Northern Ltd for a short period of time before being re-named Bluebird Buses Ltd. (the current legal name if I'm not mistaken). As far as I'm aware, the Fife entity has made no attempt since to reclaim the Bluebird title.
A few more examples that no-one seems to have mentioned yet:
- Greyhound Coaches. I can't remember where they were based originally, but they were acquired by Tayside and branded as "Tayside Greyhound" for a time. Do they still use this brand?
- Perth Panther - a brand introduced by Stagecoach Scotland Ltd for services in the Perth area before the attack on Strathtay
- Golden Eagle - a Lanarkshire independent (Salburgh based? I can't be arsed to dig out my books at this time of day)
- Beaver - used by GRT for their minibuses in the 90s
- Harrier - Central SMT
- Terrier - Highland Omnibuses
Let's not forget the manufacturers which used animal names:
- Leyland: Tiger, Lion, Leopard, Panther, Lynx, Swift
- AEC: Swift, Merlin
- ACE: Cougar
- Plaxton: Leopard, Panther, Cheetah, Beaver, Pointer
I'm sure I've missed a few.