Veeraswamy Krishnaraj

Tutelary or Family Deity (குல தெய்வம்).

Every family in Tamil Nadu has its Tutelary deity.  They may have forgotten their deity from mobility of individuals away from each other.

The individual members of the family may have இஷ்டதேவதை iṣṭa-tēvatai (Favorite deity for worship = உபாசனாதெய்வம்).

Iṣṭa Devata and Tutelary deity may be the same. The deity, after a period of worship, may bless the devotee with progeny. Once a deity establishes itself as a giver of particular boon, it becomes the deity of progeny, education, business success or even antisocial activities such as robbery... Robbers offer worship to the Vocational Deity before and after successful robbery.

Family deity or daimon is the genius (guardian deity) of an individual, family, vocation, place... Family deity as the name implies is the deity of all members of a family.

You may call the deity a patron god or goddess. Tutelary deity cane be a god or goddess.

Most of the Yogis claim Shiva is their tutelary god.

The patron saint of Catholicism mediates on behalf of a church, a town, a vocation...