Many religious traditions feature deities considered ancient or primordial. One example is Shiva, a major deity in Hinduism. According to Hindu mythology, Shiva is considered Sayambhu, meaning self-created or existing without birth from a human body. He's described as existing before creation and persisting after destruction, earning him the title "Adi-Dev," the oldest god in Hindu mythology. [Source: Many believe that God Shiva is a Sayambhu – which means He is not born from a human body. He was created automatically! He was there when there was nothing and He will remain even after everything is destructed. That is why; he is also loving called as the 'Adi-Dev' which means the 'Oldest God of the Hindu mythology.11-Aug-2017]
Other religions and mythologies also feature ancient deities, each with their own creation stories and narratives establishing their age. The concept of "oldest" varies depending on the specific belief system.