Identify the subject At beginning of film apes and chimps were really scary?

The subject of the sentence "At the beginning of film apes and chimps were really scary" is apes and chimps.

Here's why:

* Subject is the person or thing performing the action of the verb.

* Verb is the action word, which in this case is "were".

* "Apes and chimps" are the ones who were scary.