Guru Rinpoche is also known as Guru Padmasambhava. He was an 8th-century Indian master who traveled to Tibet in order to spread the Buddha’s teachings.
He relied on Vajrakilaya as his main practice and was able to subdue powerful obstructive beings in Tibet who opposed the spread of the Buddha’s teaching.
He bound them by a sacred oath to become beneficial protectors of the Dharma. These days, some say that the practice of Dorje Shugden is in conflict with the practices taught by Guru Rinpoche but historical evidence points to the contrary.
In fact, many devotees of Guru Rinpoche worship Dorje Shugden as their main protector. There are even a number of ancient thangkas that depict Dorje Shugden as one of the prominent protectors of the Nyingma tradition.