Vellattam is an invocative ritual held prior to the actual Theyyam performance. Through this ritual, the mortal human being is believed to get transformed into the divine self. It is equivalent to the Thottam, the invocatory chant, but is more colourful and vigorous.
Thacholi Othenan was a legendary hero who is believed to have lived during 16th century in North Malabar region of Kerala. Ballads of northern Kerala or Vadakkanpattu laud the feats of Thacholi Othenan. The Vellattu ritual held prior to the Othenan Theyyam is Vellattu Othenan.