Blur

Blur is a Phaser and is a member of the Black Swan's Collective. To disguise himself, he breaks his body down and only reforms partially, leaving the only parts of his body visible as splotches of color and blurred lines. He was first introduced in Neverseen and makes appearances in Lodestar and Nightfall.

In Nightfall, Blur says that his identity comes with a "looooooooong explanation.”

Fan Theories - Blur's Identity
Please note: Blur’s identity is currently unknown.

Jensi's older brother

The Theory - It was mentioned in the books that Jensi's older brother is a Phaser but nothing else is mentioned about him. Shannon does not just drop facts randomly so this leads many readers to believe that Jensi's older brother is Blur. In fact, Blur shares several similarities in appearance with Jensi himself, and Jensi and his brother probably have some similar features. In Nightfall, on their trip to Ravagog, Sophie sees some water wash over Blur, causing him to lose his concentration and slip a little, letting reveal a little of his looks. Sophie comments on how he is not only skinnier and shorter then Sophie thought, but his round cheeks and full lips looked familiar.

Quan Song

The Theory - As said above, when the water washed over Blur, Sophie could see his round cheeks and full lips. A FANDOM User states (on the Quan page's comments) how Linh and Tam also look like this, and therefore Blur could be Quan. It is also never mentioned in the books what ability Quan has therefore there is a chance he might be a phaser.