Lurker
Noun · Hacker Culture
Definitions
A person who reads community discussions, mailing lists, forums, or chats regularly without posting much or at all. In tech communities lurkers are often numerous and valuable, even if they are less visible than active contributors.
In plain English: Someone who follows an online community quietly without posting much.
Example: "I was a lurker in the Python mailing list for years before I ever sent a patch."