Meg Dwyer is the voice acter of Nina. She has been the only voice actor for Nina, since Ep.2 Girl On Xbox Live. From what we believe she has only voiced Nina but its possible thats she's voiced Video Game scenes and brief characters who appear for only a matter of seconds.
Nina is the third most seen characters appearing many times in the Sanity Not Included series. She's in a weird relationship of some sorts (with benefits only really being sex and not knowing each other too well, though they do live in the same house).
During Season 3, Meg was replaced by MistiDawn for the voice of Nina. The pilot episode of Season 4 revealed that Meg had returned.
Meg's Youtube channel is "shamegmeg" butshe is rarely active on the website.