The Lar Familiaris (literally translated as the Lar of the Family)is the protector of an individual Roman's family or bloodline.

The Lar Familiaris would protect those who were reverent towards him and offered him sacrifices. To those who forgot the Lar and did not remember to exalt him, he would not offer them his help. This is evident in The Aulularia of Plautus (Lines 1-36). The Lar knew the grandfather of Euclio had buried gold in the hearth, because the grandfather had begged the Lar to hide it for him. When the grandfather died, the Lar did not show his son where the gold was hidden because the son, or the father of Euclio, did not remember the Lar daily. The Lar kept the gold hidden until Eulcio's daughter, who was always very pious, came into a situation where she needed a dowry. Only then did the Lar help Euclio to find the gold, so his daughter could have a dowry. The Lar also made a wealthy bachelor from next door fall in love with the daughter and want to marry her. This is proof that the Lar would generously help those who honored him zealously. To those who would not offer him thanks, he would turn his back on them.

Plautus describes the Lar Familiaris as a young, slender figure clad in high boots, short tunic, and belted undergarment. Garlands adorn his head. He is lithe, graceful, and nimble.