Gajan or Shiva gajon is a Hindu festival celebrated mostly in the Indian state of West Bengal. It is associated with such deities as Shiva, Neel and Dharmaraj. Gajan spans around a week, starting at the last week of Choitro continuing till the end of the Bengali year. It ends with Charak Puja on the last day of Chaitra, the last month in the Bengali Hindu calendar. The next day is Poila Baishakh, the first day of Bengali New Year. Participants of this festival is known as Sannyasi or Bhakta. Persons of any gender can be a participant. The complete history of the festival is not known. The central theme of this festival is deriving satisfaction through non-sexual pain, devotion and sacrifice.

The word gajan in Bengali comes from the word garjan or roar that sannyasis (hermits) emit during the festivities. Alternatively, the word gajan is considered a combination of parts of two words - 'ga' is from the word gram meaning village and 'jan' is from the word janasadharan meaning folk. In this sense gajan is a festival of village folk.

The devotees madly dance, shout and roam around villages, assuming themselves as Nandi and Bhiringi (great devotees of Lord Shiva). This Gajan festival is celebrated in different ways in West Bengal. In some villages, children portray mostly as Lord Shiva or Lord Krishna, wearing eye-catching costumes and their faces are painted in blue or white. In some villages, devotees play with skulls pretending to be the real devotee of Lord Shiva.

Apart from the costumes, the songs in Gajan performances are equally significant, for they express the social, religious and political status of these rural natives who have been subject to all the evils associated with social stratifications, including but not limited to exploitations by the upper classes, and political hegemony.