Ganesh

The great god Shiva lived with his consort Parvati on mount Kailash. Shiva used to leave his home and Parvati for long periods of time to meditate atop the mountain. During one of these stints Parvati decided to take a bath but without Shiva there to protect her she decided to create someone to guard her door. She reached around and gathered the dirt from the back of her neck and formed it into the shape of a small boy. She breathed life into the figure and he suddenly came alive!

Ganesh was the name given to little boy and Parvati loved him very much for he was her son. She handed Ganesh an great war mace and told him that under no circumstances is anyone allowed to enter her bath house while she was inside. Ganesh took his orders and stood outside of the door turning away all visitors that had come to see the goddess. 

Shiva returned from meditation atop mount Kailash and wished to see his consort however, a young boy blocked his way. The boy told Shiva that Parvati was not taking any visitors at the moment and to please come back later. Shiva, shocked, told the boy "I am Shiva, The God of gods and the destroyer, and I have come to see my consort. Step aside young man." However Ganesh politely informed him again that Parvati was not taking any visitors and to come back later. "You have made a grave mistake young man." Shiva said as he produced his trident and a great battle ensued.

Shiva and Ganesh were both very skilled warriors and neither could gain the upper hand on the other. Shiva would swing his trident but Ganesh would nimbly jump over it simultaneously bringing his mace down to crush Shiva's skull to which he would dodge. The two were evenly matched until Shiva decided to use his powers of illusion to distract Ganesh. In that instant Shiva swung his trident and lopped Ganesh's head clean off. 

Parvati hearing the noise outside of her bath got dressed and emerged to see Shiva standing over the lifeless body of her son.  Parvati was in shock and she looked at Shiva and said "You have killed my only son, the only reason I had for living." She was distraught and set out to destroy the universe.
Shiva's fellow gods urged him to stop Parvati but when he tried to reason with her she would not listen.  Shiva knew the only way to make things right was to bring their son back to life so he gathered a group of followers to find the head of the young Ganesh. They searched for days but could not find the head anywhere so they returned to Shiva for further instructions. 

Shiva was puzzled as to where the head had disappeared to but nonetheless he was wise and told his men to cut off the head of the first animal they see.. The men embarked again and within a short while they came across a slumbering baby elephant. They removed the head of the elephant and brought it back to Shiva to which he placed on the shoulders of the headless boy. Shiva breathed life into the boy and he arose and began to dance for he had gotten a second chance at life. From that day forward Shiva accepted Ganesh as his own son and decreed that those who were to worship him must worship Ganesh first.

Ganesh is known as the remover of obstacles. His statues are located near the entrance of almost all shrines devoted to Shiva.