Who will be cast as Elliot Rodger...
...in the inevitable made-for-TV and/or straight-to-video movie(s) likely to be already in development? My guess would be an unknown rather than a familiar face. He was biracial.
In case you're wondering, yes, he does have a bio on IMDb which has not yet been updated (or deleted).
http://www.imdb.com/name/nm3633817/?ref_=nmbio_trv_1
"Talk amongst yourselves." ~ Linda Richman