Similarities:
-Both have dark themes (TBK being darker)
-Both have main leads who are not who they may first appear to be (though the two are very contrasting individuals once we see who they are)
-Both have dark themes with murder and cruelty (being vague as it's been a while since I watched Beyond Evil)
-Both have AMAZING cinematography that really bumps the show up from being an amazing show to being pure masterpieces in their own regards.
-Overall there is more focus on male characters with main leads being men
-There is little to no romance in either of the shows
-You can interpret 2 characters within each show as being very similar/different sides of the same coin to each other.

The main leads are very similar. They both have a very dark theme and are heavy watches, addictive and will make you want to binge-watch. Strangers from Hell has an alternate title that I've always felt suits the show much better which is 'Hell is other people'. These are both psychological and play on the 'seemingly innocent quiet kid/guy' trope who is 'not as he seems'. Strangers from hell is more 'current' for the time place it is set in. There are cats in both shows!