In Hinduism who is the preserver?

Lord Narayana is the preserver.

Every Hindu knows Vishnu, also known as Narayana, as the preserver.

This is because he is symbolic of the Semi voluntary force. This force makes everything in our life to stay between an upper and a lower limit, due to the presence of the Negative and the Positive attitudes. Vishnu would not allow as to cross these limits under normal conditions.

Vishnu - the transformer:

Due to incarnations, Vishnu enables us to change enormously between these two limits.

1. Rama, symbolic of the negative attitude, enables us to be totally satisfied with whatever we have and be adherent to dharma even under extreme conditions.

2. In marked contrast, Krishna, symbolic of the Positive attitude, enables us to succeed at all costs.

3. Venkateshwara, another incarnation of Vishnu, enables us to have just a virtual existence between the attitudes and acquire wealth compulsively yet safely. He is undoubtedly, the most acceptable Hindu god in this materialistic world.

Thus, even though Vishnu is known as the preserver, he allows us to change our life more than any other Hindu god.

The actual Hindu preserver god:

The Hindu god, which eternally doesn't allow even the minutest change in our life under any condition, is Brahman. Thus, Brahman is the absolute and eternal Hindu preserver, of dharma and of our life.

The popular preserver:

Since most Hindus can't understand Brahman and don't want the rigidity Brahman gives, they consider Vishnu himself as the preserver.