Nawar Al-Awlaki, a US citizen, was killed January 29, 2017 in a raid on an Al Quaeda training facility in Yemen along with as many as 29 other (Yemeni) civilians.
From the article:
The raid in Yemen was described as "risky from the start and costly in the end"; the "botched" operation raised questions about the choice to go forward with the raid "without sufficient intelligence, ground support or adequate backup preparations".
Her father Anwar, also a US citizen, was killed by drone strike in 2011.
People at the time criticized Obama for ordering the drone strike and killing a US citizen, which is valid and one of the great failures of his term, but Nawar's murder was worse in every way and I only ever see it as a footnote.