That is, I believe, a Genestealer and it is genuinely frightening in appearance! Sculpted by Farhad Nojumi, this xenos will hopefully be appearing in The Lord Inquisitor film, where the magic of animation will make it even scarier.
The design of the Genestealer is intriguingly human, reminding me of the background of Genestealers and how they got their name in the first place. Genestealers have always been to me the scariest of the Tyranids and that is the reason! A reason this CGI render seems to embody.