The Blob

The Blob is found in designs where one class monopolizes the processing, and other classes primarily encapsulate data. The key problem here is that the majority of the responsibilities are assigned to a single class.

Related smells: Insufficient Modularization God Class Large Class Too Large Packages/Subsystems

Reference

W. Brown, R. Malveau, H. McCormick, T. Mowbray, “AntiPatterns: Refactoring Software, Architectures, and Projects in Crisis”. John Wiley & Sons, 1998.