Rubber mask

A rubber mask is a mask made of rubber. Typically, these are made of latex or silicone rubber and designed to be pulled over the head as a form of theatrical makeup or disguise.

The theatrical makeup used by Michael Crawford when he played the Phantom of the Opera started with a latex skullcap. More latex strips were then added for the disfigured face. The latex was then covered and coloured with cosmetics for the full effect.

Materials
Rubber masks are typically sculpted out of clay, and then cast into either a latex or silicone final piece from a mold.

Latex
Most of the masks that are seen around are more than likely going to be made out of latex. Latex is a cheaper rubber making it a much more affordable material to produce. It is generally a lot easier to work with than silicone. It has a fair amount of give and is more breathable on the wearer's skin.

Silicone
For more professionally made masks, silicone is likely to be the rubber of choice due to its flesh-like, translucent qualities and its ability to "hug" the wearer's face which allows it to move along with different expressions. Silicone tends to be much higher in price, but has a much more realistic appearance and texture.

Don Post
Don Post, also known as "The Godfather Of Halloween" had a significant role in coming up with some of the very first over-the-head latex masks and became a staple in the history of rubber masks and Halloween merchandising. Post's masks date back to 1938 when he began his company creating and selling carnival masks.

It wasn't until his son, Don Post Jr., took over the company in the early 1960's that it began to take focus on the Halloween/horror industry.