Shiva is considered as the destroyer of the universe, in Hinduism. Shiva is a complex god, in terms of nature and represents contradictory qualities, being the destroyer and the restorer simultaneously. There are numerous legends surrounding Lord Shiva and his powers. Here're a few popular stories of Lord Shiva.
This is an interesting story regarding the worship of Lord Shiva in the phallic form. It is believed that once Brahma and Vishnu, the two deities of the Trinity, got into an argument regarding their supremacy. Lord Brahma declared himself to be more admired, being the creator. While the preserver, Vishnu, pronounced that he commanded more admiration. Just then a huge pillar of fire (lingam), called as Jyotirlinga, appeared in flames, before them. This Lingam enthralled both Brahma and Vishnu, with its hastily increasing size.
With this incident, they forgot their quarrel and decided to find its size. Vishnu took the form of boar and went to the netherworld. Brahma assumed the form of a Swan and flew to the skies. However both of them were unsuccessful in completing the self-assumed tasks. At that time, Shiva appeared out of the lingam and acknowledged that he was the progenitor of both, Brahma and Vishnu. So, he should be worshipped in his phallic (lingam) form, and not in the anthropomorphic form.
Here is one more interesting story of Lord Shiva, showing his merciful nature. Once a hunter was wandering in a dense forest, to chase a deer and suddenly he found himself on the banks of river Kolidum, where he heard the roar of a tiger. In order to defend himself from the tiger, he climbed up a tree close by. The Tiger sat on the ground below the tree without the purpose to leave.
The huntsman stayed at the tree whole night and to keep himself awake, he plucked one leaf after another from the tree and threw it down. There was a Shiva Lingam under the tree and gracefully the tree turned out to be a ''bilva'' tree (leaves of this tree are adored by Shiva). Without any knowledge, the huntsman had delighted the deity by pouring Bilva leaves all night. With the arrival of the sun, the hunter looked down and found the tiger gone. In its place, Lord Shiva was standing and he prostate before the lord. With Shiva's blessings, he attained salvation from the bondage of the material world.