I've seen two questions that both ask this!! Just look it up!!
If you are so helpless, its Ignatius.
His first name is Perseus (like in the myth of Perseus, Percy is short for Perseus) and his last name is Jackson (since his mother is Sally Jackson and Poseidon doesn't have a last name). His middle name has not been mentioned. Perseus Jackson
The author made the name up. Within the story, that was short for "Perseus", being named after a figure of Greek legend.
In fact, Percy Weasley is Percy Weasley's real name.
Percy Sutton's birth name is Percy Ellis Sutton.
Percy Helton's birth name is Percy Alfred Helton.
Formal, the common name for Perseus today is Percy. Percy is short for the English name of Percival. Perseus is probably not a common name, except perhaps in Greece.
Percy Rodrigues's birth name is Percy Rodrigues.
His first name is Perseus (like in the myth of Perseus, Percy is short for Perseus) and his last name is Jackson (since his mother is Sally Jackson and Poseidon doesn't have a last name). His middle name has not been mentioned. Perseus Jackson
The author made the name up. Within the story, that was short for "Perseus", being named after a figure of Greek legend.
In fact, Percy Weasley is Percy Weasley's real name.
Percy Crosby's birth name is Crosby, Percy Leo.
Percy Saltzman's birth name is Percy P. Saltzman.
Percy Sutton's birth name is Percy Ellis Sutton.
Percy Standing's birth name is Percy Archibald Standing.
Percy Aires's birth name is Percy Aires Loesh.
Percy Ames's birth name is Percy Freeman Ames.
Percy Barbat's birth name is Percy Dewitt Barbat.