Signer

noun

1. One who signs; specifically, one who writes his name as a signature: as, the signer of a letter; to get signers to a petition; the signers of the Declaration of Independence.
2. One who signs or subscribes his name.

   "a memorial with a hundred signers"

3. One who signs something.
4. One who uses sign language.
5. someone who can use sign language to communicate