What is the abstract noun from common author?

The abstract noun from "common author" depends on what aspect of "common author" you want to emphasize. Here are a few possibilities:

* Authorship: This is the most general abstract noun, focusing on the act of writing.

* Popularity: This emphasizes the idea of being widely known and read.

* Prevalence: This focuses on the common occurrence of authorship.

* Commonality: This emphasizes the shared characteristics of authors.

The best abstract noun will depend on the specific context and what you are trying to communicate.