The five Tathagata [or also: Dhyani] Buddhas are the white Vairocana, the blue Akshobhya, the yellow Ratnasambhava, the red Amitâbha and the green Amoghasiddhi.
They are not historical Buddhas. These Buddhas are visualized in the course of a meditation.
Each of the five Tathagata Buddhas is associated with certain symbols, characteristics and cardinal points and embody one of five wisdoms.
By associating the Buddhas with the five cardinal directions [The center is considered the 5th cardinal direction] ] they are rulers of the five cosmic realms of "ether, water, earth, fire and air".