There are five different characters in the Marvel Universe known as White Tiger: White Tiger from "Heroes for Hire", Kasper Cole, Hector Alaya, Angela del Toro, and Ava Alaya.
White Tiger from "Heroes for Hire" was an actual white tiger who was captured and experimented on, gaining the ability to take on the form of a woman.
Kasper Cole appeared in the "Black Panther" series. He was a police officer who became a vigilante after the death of his partner. He gained superhuman abilities by convincing the Black Panther to allow him to participate in the Wakandan Rite of Ascension that allowed him to eat the heart-shaped herb from which the Black Panther withdrew his powers.
Hector Alaya was the first White Tiger to gain his powers from the Jade Tiger, an enchanted statue that granted superhuman abilities to its user. He appeared in the "Daredevil" series.
Angela del Toro is the niece of Hector Alaya, and the second White Tiger who used the Jade Tiger to gain superhuman abilities after the death of her uncle Hector. She fought alongside Daredevil like her uncle.
Ava Alaya is the third White Tiger and the younger sister of Hector Alaya; and aunt to Angela del Toro. She appears first in the "Avengers Academy" series as a student. Like her relatives, she uses the Jade Tiger relic to gain superhuman abilities.