Fluffy

Fluffy the Cerberus from harry potter is currently one of the more known because of the harry potter franchise. Fluffy isn’t seen that much within the films but when he is seen you can see the personality differences between the heads. When fluffy wakes up later on in the film all three heads are aggressive at once so it their must be away all three heads are connected.

https://www.youtube.com/watch?v=VhLScMxedXI