From Britain or Brittany
A modern spelling variation of Brittany, originally a geographic surname referring to people from the region of Brittany in France or from Great Britain. The name gained massive popularity in the late 20th century before evolving into various phonetic spellings.
Less common today
Brittny isn't in the latest US Top 1000. It last peaked at #592 in 1990.
American socialite and reality television personality
US births per 5-year period, 1990βpresent (SSA data).