Answer:
It is a complex sentence.
Step-by-step explanation:
The first portion of the sentence, "I won't go to the movies," is an independent clause. It can stand on its own, and still be a complete sentence.
The second portion of the sentence, "Unless you come as well." is a dependent clause. It cannot stand on its own, since it is not a complete sentence.
When a dependent clause and an independent clause are together in one sentence, it makes up a complex sentence.
Hope this helped!
~Jinachi~