A temporal causality loop is a theoretical phenomenon, which is said to occur when a chain of cause-effect events is circular. For instance, if event A causes event B, and event B causes event C, and event C causes event A, then these events are said to be in a causality loop.

A fictional example of a temporal causality loop occurs in the movie The Terminator. In it, John Connor sends a man back in time to guard his mother Sarah's life from a assassination attempt. That man, who impregnates her, turns out to be John's father. Sending him back (event A) caused John to be born (event B), which eventually caused event A.

A causality loop diagram (also known as a causal loop diagram) is a scientific diagram for showing the influence of two interrelated variables.