In 2020 Women in Red ran an event which focussed on improving women's biographical content for the countries with the lowest percentage of articles on English Wikipedia. This listing was first created by MarioGom. I really enjoyed the initiative, so have been carrying it forward, with a focus on the 20 countries with the lowest percentage of representation. Since articles are being added to Wikipedia all the time, the countries alter periodically.
As this is a personal project, I bend the rules a little and include on my listing pages related to women, as well as biographies. After recent discussion, it seemed like a good idea for me to keep a track of my efforts.
There is also a humaniki version of this data.