According to the Fullmetal Alchemist Wiki, Rose, the character who appears in the Lior arcs of FMA, has "Thomas" for a surname. While the Wikipedia entry on her simply refers to her as Rose, a quick Google search for
fma rose yields several results for her as "Rose Thomas".
However, I don't recall Rose ever being referred to as anything other than "Rose" during the course of either Fullmetal Alchemist anime series or in the manga. (It is of course possible that I don't remember the 2003 anime very well, since I binge-watched it a year ago and might have missed some details.) What's the origin of her supposed surname, and is this even something "official" in any capacity?