Dīpankara is one of the Buddhas of the past. He is said to have lived on Earth one hundred thousand aeons ago. According to some Buddhist traditions, Dīpankara was a Buddha who reached enlightenment eons prior to Gautama Buddha, the historical Buddha.
Generally, Buddhists believe that there has been a succession of many Buddhas in the distant past and that many more will appear in the future; Dīpankara, then, would be one of numerous previous Buddhas, while Gautama was the most recent, and Maitreya will be the next Buddha in the future.
Chinese Buddhism tends to honor Dīpankara as one of many Buddhas of the past. Dīpankara, Gautama, and Maitreya are "the Buddhas of Three Times" in Yiguandao.