Illusion

From The 4400 Wiki, a fan encyclopedia that anyone can edit.

Illusion is a promicin-induced ability that allows its user to create perfect illusions of people or objects. The person or object generated by this ability would be indistinguishable from the original, as it takes form and substance from the memories of whatever people are in the area. However, the illusions only remain as long as its user is awake, and the user himself will suffer tremendously due to the effort, as he will be unable to fall asleep or lapse in concentration for even a second for risk of the illusion losing integrity. The user also develops a minute telepathic link to people near the illusions, receiving information.

4400 Byron Lillibridge has this ability.