Board Thread:Questions and Answers/@comment-30381369-20160826051438

An ecumenopolis it's a 100% urbanized and overpopulated planet/planetoid/moon (including underground, surface and in some cases, seas).

Some notable examples outside marvel are curusant of star wars and the earth in mass effect.

https://en.wikipedia.org/wiki/Ecumenopolis

Artificial planets like chandilar also count. 