Alyssa is a character from Tiberian Twilight.
Alyssa is a mysterious character, tied to the even more mysterious events tied to TCN Node #51. Before its construction began in 2072, a year earlier, GDI forces started mysteriously disappearing. Starting with a convoy carrying building materials, through an Orca recon group, all the way to a Mammoth tank-led strike force. At the same time, many troops on patrol duty near the Node construction site, reported seeing the silhouette of a woman, walking calmly through the snowstorm in the distance.
With morale running low and many soldiers outright refusing to patrol the TCN Node area, the local GDI commander was forced to request assistance from a Nod detachment. Out of the fifteen soldiers that left to scout the area, three returned, accompanied by The White Lady, as the mysterious woman came to be known. Records of the meeting were sealed by Kane post-factum and only reliable sources are eye witnesses. They agree that the woman introduced herself as Alyssa and that she has brought a gift for Kane. Immediately thereafter, a vehicle unstealthed behind her, a new, 4th generation stealth tank, painted snowstorm white, immediately relocated to a secret facility for reverse engineering.
Sometime after this event, she was tasked by Kane to raid the Echo storage facility that housed a functional Obelisk of Darkness. The White Lady was ultimately successful in her mission and made the attack appear as if it was an assault by Nod Separatists on the GDI installation.
It is unknown what happened to Alyssa after this, but, since she is part of Nod, it is reasonable to suggest she has probably now 'Ascended' with the rest of the Brotherhood.
There are many theories concerning Alyssa. Some believe she was the commander of a Nod installation at TCN Site #51, where one of Kane's Vaults of secret technology was located. Another theory is that she is a Human-Scrin hybrid, born from Nod's twisted experiments in the frozen wastes, who integrated Scrin technology into her vehicle. Yet another proposed theory is that she is a descendant of Anton Slavik, raised in the shadows to one day become Kane's most brilliant general (which also tends to be the most popular).
Theories abound, but the White Lady remains a mystery, one to which only Kane himself holds the key.