There is a strange symmetry to Zachary Quinto and Eli Roth. Roth is best known for his horror movies, where he creates ghoulish characters and murderers. Quinto has spent much of his career doing movies or shows like 'American Horror Story', where he always seems to be playing murderers (although thankfully not on the Enterprise when he's playing Spock in 'Star Trek'! It's a wonder that the two have never worked together. Maybe it would be too confusing for everybody on set, because they really do look like brothers.
Roth does occasionally make appearances in front of the camera as well as behind it, but we suppose there's no great call for him to do it more often when Quinto is walking around with the same face and does the job better. He's so committed to the horror genre that despite working since 1998, he didn't release a film with a rating lower than 'R' until 2018!