Elena Delle Donne of the WNBA's Chicago Sky and all-time NBA great Larry Bird have a few things in common. Both had intended to play college ball for premier programs (Delle Donne for Connecticut in 2008, and Bird for Indiana in 1974), but left after a short time on campus. Plus, they are both great free-throw shooters.
Bird resurfaced at Indiana State, where he led the Sycamores to the 1979 NCAA championship game. He then had a long and successful pro career with the Boston Celtics, during which he once made 71 straight free throws, seven short of the NBA record at the time.
Delle Donne likewise returned to collegiate competition, in her case with Delaware. According to this webpage, which catalogs consecutive-free throw records at different levels of competition, Delle Donne is tied for the ninth-longest streak of made free throws in women's NCAA Division I history, at 52. She also once made 80 straight from the stripe in high school, one of the longest streaks at that level.
This summer, Delle Donne hit 50 straight free throws for Chicago, giving her stretches of 50 (or more) straight at three levels of play (high school, college, and pro). I don't know how many other players -- male or female -- have achieved this feat, but I doubt there are too many. (According to the free-throw records website, J.J. Redick of the L.A. Clippers has exceeded 50 straight in high school and college; perhaps one day he'll reach that mark in the NBA.)
Going back to Delle Donne, her game-by-game log documents how she hit 50 straight free throws during the current WNBA season. On May 21, she hit 5-of-6 from the stripe; according to the play-by-play sheet, her lone miss occurred on her second attempt, meaning that she made her last four free throws in that game. Her next several games featured free-throw statistics of 9-9, 0-0, 8-8, 16-16 (a WNBA single-game record), 0-0, 7-7, and 3-3. It wasn't until August 3 that Delle Donne missed again. As shown in the play-by-play for this game, she made her first three free-throw attempts, missed, and then made another, for a 4-5 night. Adding up the numbers of made free throws shown in red, you get 50.
The WNBA record for consecutive made free throws is 66, by Eva Nemcova of the now-defunct Cleveland Rockers, spanning the 1999 and 2000 seasons. With Delle Donne's streak of 50 straight free throws having ended, she'll have to mount a new challenge to break Nemcova's record of 66; I wouldn't bet against it!
