Though Dara in the U.S. would be considered strictly a girls' name, it's a boys' name in Ireland, where it's on the Top 100 along with variations Daire and Darragh. (It should be noted that Dara is also a boys' name in many non-Western cultures, meaning leader in Punjabi and wealthy in Persian. In Iran, Dara and Sara are the Islamic Ken and Barbie.)
Though Dara was an (extremely wise) male figure in the Bible, this name couldn't feel more feminine to modern English speakers. The Irish Gaelic version, Darragh, is well-used in contemporary times for boys. In the U.S., though, any Dara would definitely be assumed to be female.
The cousin-name Daria was featured a few seasons ago as the smart and cynical star of her own eponymous animated MTV show.