Nawar al-Awlaki, also known as Nora, was among the non-combatants killed - along with several women - in Sunday's military operation at an Al-Qaeda camp in Yemen.
he was the daughter of Anwar al-Awlaki , a dual US-Yemeni citizen who was the first American to die in a US drone strike.
The other American citizen killed in the raid was Chief Petty Officer William 'Ryan' Owens, 36, who died during a gun battle.
Her 16-year-old brother, Abdulrahman, also a US citizen, was killed in a drone strike in Yemen two weeks after their father died in 2011.
Anwar al-Awlaki, 40, was born in the US state of New Mexico and split his youth between the US and Yemen, where his parents are from, before returning to America as an adult and working as an imam and lecturer.
He left the US in 2002 while he was being monitored by authorities, and spent some time giving lectures at mosques in the UK before returning to Yemen in 2004.
The al-Qaeda leader and propagandist was considered a potential successor to Osama bin Laden .
Yemenis claimed that as many as 59 combatants and civilians, including women, were killed.
US officials said some of the women were combatants and shot at the SEAL Team Six members.
Nawar's grandfather, Nasser al-Awlaki, who once served as Yemen's agriculture minister, claimed to NBC News the girl was killed by a bullet to the neck as she and her mother were sitting in a house.
He claimed other children were killed in the raid and that SEALs entered another house and killed everyone inside, including women, before burning it.
During the ensuing firefight Owens, of Peoria, Illinois, was killed. He was assigned to a special warfare unit based on the US East Coast.
Defense Secretary Jim Mattis said in a statement: "Ryan gave his full measure for our nation, and in performing his duty, he upheld the noblest standard of military service.
"The United States would not long exist were it not for the selfless commitment of such warriors."