Jenny enters the ranks of the Companions in an unusual way, she's born at the beginning of "The Doctor's Daughter" from a tiny bit of the Doctor's DNA. So she just has a first name, and no last name. Usually in that case the person would use the paternal last name, but the Doctor doesn't have a last name either! Jenny appears to be a Time Lord, at least she has two hearts and a way high IQ, but when she's shot and killed toward the end of the story she doesn't regenerate like the usual Time Lord. After the Doctor, Donna, and Martha leave in the TARDIS Jenny does come back to life so maybe she has a better regeneration method than other Time Lords, or maybe this is more of the TARDIS's doing. In the end, Jenny steals a space ship and takes off for Who knows where. She'll definitely be back.
Georgia Elizabeth Moffett (born Dec 25, 1984 in West London) is an English actress. Moffett is the daughter of actor Peter Davison, the fifth Doctor, who was born Peter Moffett. That caused comments along the lines of, "The Doctor's daughter was played by er...the Doctor's daughter."