Greta Gerwig is an actress whose involvement in movies is very hands-on.
She has made numerous independent films, co-writing some of the movies she appeared in and also co-directing one movie, 2008's Nights and Weekends, about a long-distance romance. (She played the role of Mattie, the woman in the affair, in that film.)
She's gotten several award nominations from film critics' circles for her performances in 2010's Greenberg (starring Ben Stiller as the title character) and 2011's Damsels In Distress, but she's only won one award, a Best Actress prize for the latter movie from the Dublin Film Critics circle. No Oscars yet, though.
But, as she is young and has likely not peaked yet, Greta Gerwig is someone to look out for. :-)