I was born Adam Wayne Smyth. My middle name was my father's first. I don't know where they got Adam, but since my sister is Amanda, I imagine they just didn't make it past the first page of whatever book they were looking at.
I'd never been particularly fond of my name, for various reasons. Adam Smith was philosopher interested in economics, and his socioeconomic views are, to say the least, distasteful to me. Nobody can spell Smyth properly - I can spell it for them as I tell them my name, and people will still write or type it wrong. Everybody assumes they know how to spell it, and thus get it wrong.
Marty is better. After I started going by Martian online, it didn't take long for people I knew there to start calling me Marty in person. Marty Smyth sounds better. But the problem of Smyth persists.
So, I'd been meaning to change my name for a long time. The first name was obvious: Martian or Martin. Martian would confuse people to much, so, ok, Martin. The last name took a while to figure out. I had polls up for a while, added suggestions, filtered and rearranged. Finally, I settled on Tithonium, as in Tithonium Chasma at the western end of Valles Marineris, just east of Noctis Labyrinthus. A middle name wasn't of much concern, I was happy to do without, until I happened to make it onto the high score list on the Robotron machine at work. Since I started going by Marty, I've always used MRT as my initials in such things. So, I realized, I had to have a middle name that started with R. Finding a good idea was difficult, including the usual nonsense with polls, but in the end I went with Regulus.
It was only later that I realized that Regulus is latin for 'little king' or 'prince', and incorporated it into my Hegemon of Mars backstory, retconning that I was Martin, Regulus of House Tithonium.