Thirteen Golden Dharmas
In Tibetan: gser cho chu gsum
These thirteen tantric practioners were transmitted to the Sakya lineage from India and Nepal, and it's considered that the Sakyas are the main holders and maintainers of these traditions.
The reason they are called golden is that the Tibetan students had to pay a lot of gold for obtaining these teachings from the masters in India. Tibet was actually famous for its rich gold deposits.
There are actually various sets of Thirteen Golden Dharmas. Standard to all these sets are:
The Three Red Ones: Vajrayogini of Naropa, Vajrayogini of Indrabhuti, and Vajrayogini of Maitripa. These three are from the Chakrasambhava cycle of tantras.
The Three Small Red Ones: Kurukulla Tara, Red Vasudhara, and Tinuma.
The alternate deities are: Simhamukha and Amaravajradevi from the Chakrasamvara tantras, and Amitayus from its own tantra.