Anti-pattern central to Chikahiro Tokoro's talk. A single object/model that does too much: tightly coupled, poor cohesion, unclear boundaries, a 'ball of mud'. Symptoms in Rails: a class with many concerns, many related models, many callbacks, thousands of lines, and many columns — changing user registration mysteriously breaks payments. Complaints about monoliths (not scalable, hard to debug, unclear boundaries) are usually symptoms of God objects. Trying to break a system with God objects into microservices produces a distributed monolith. Fixing them requires better modeling (DRY as knowledge, DDD) and incremental refactoring with clear business merit.