Necro time!
I got mine from Spectral and Lion.
I pick Spectral from Spectral Theory, one from my thesis material and Lion is just to make it sound badass...
I made that username to remind me that my thesis is haven't finished until last two months, so if I see my username I remember my thesis and start working on it.
Turn out, it just useless X)
...and after some coincidence, I discovered that my great great grandfather's name got some "Lion" in his name. So, I kind of descendant of the Lion and my username is way more perfect now