Jagannatha and Ganesha
Once a worshipper of Ganesha, a demigod named Ganapati Bhatta, came to Jagannatha Puri to participate in Snana Yatra. But, when he saw that Lord Jagannatha did not have an elephant head, he was very disappointed and withdrew from the festival. Lord Jagannatha, being the paramatma in everyone’s heart, immediately understood Ganapati Bhatta’s desire and the reason for his disappointment. Lord Jagannatha assumed the form of a brahmana and went to Ganapati Bhatta, who had left the temple and was preparing to leave Puri. As a brahmana, He convinced Ganapati Bhatta to return to the temple. Ganapati Bhatta came to the temple again in the evening. When he received the darshan of Lord Jagannatha, he was pleasantly surprised to see that Lord Jagannatha had an elephant head. Simply to please His devotee, Lord Jagannatha appeared in a specific form called hathi vesa. This pastime of Lord Jagannatha also illustrates that if someone worships the Supreme Personality of Godhead, Sri Krishna or Lord Jagannatha, there will be no need to worship demigods, because Krishna is the source of all powers and all demigods receive their powers only from Krishna.
During the Govardhana pastimes, Lord Krishna also demonstrated that the worship of demigods is unnecessary.