Fundamental attribution error

In social psychology, the fundamental attribution error is a cognitive attribution bias in which observers underemphasize situational and environmental factors for the behavior of an actor while overemphasizing dispositional or personality factors. In other words, observers tend to overattribute the behaviors of others to their personality (e.g., he is late because he's selfish) and underattribute them to the situation or context (e.g., he is late because he got stuck in traffic).

Source: Wikipedia — Fundamental attribution error (CC BY-SA 4.0)