His entire name is Damon Lee Fizzy. I don't think Damon ever said in his videos that Fizzy was his last name, but I'm pretty certain "Fizzy" accually is his last name.
It is Francesco. Damon's full name is Damon Francesco Salvatore.
DeeFizzy's real name is Damon Fizzy.
Les Damon's birth name is Lester Damon.
Damon Vracin's birth name is Damon A. Vracin.
Damon Pampolina's birth name is Damon Phillip Pampolina.
Damon Kuenzler's birth name is Damon Biviano Kuenzler.
Damon Lindelof's birth name is Damon Laurence Lindelof.
Damon Lipari's birth name is Damon Gerard Galinis.
Damon Runyon's birth name is Runyan, Alfred Damon.
Damon Huard's birth name is Damon Paul Huard.
Damon Berryhill's birth name is Damon Scott Berryhill.
Damon Elliott's birth name is Damon William Elliott.