Gampopa
Gampopa unified the stepwise path of the Kadampa tradition, with which he had grown up with the meditations focused on Mahamudra, which he had learned from Milarepa, from whom he received the full Kagyü transmission.
Also, the Ngöndro idea had its origin in Gampopa or rather in Milarepa, who showed his scarred behind to him in the moment of goodbye. Gampopa understood the information: “Meditate!” and increasingly instructed his students to practice on one of the meditations we now call Ngöndro. Both Gampopa’s students and he himself had long periods of time to practice in solitude.
In addition, as a monk, Gampopa rounded off the picture of the three types of practitioners at the beginning of the Karma Kagyü lineage: he was a monk, his teacher Milarepa a yogi and Marpa a layman.