Halo Alpha
Halo Alpha

Graphic Halo Halo Alpha has a collection of quotes related to Sandra Tillson on its quotes page.

Doctor Sandra K. Tillson[2] (SN: CC-728304)[1] was the leader of a team of scientists serving onboard Ivanoff Research Station, a UNSC research facility near Installation 03.


Early career[]

Born on Coral on May 14, 2506, Sandra eventually gained a scholarship to the Pegasi Institute[1] where she studied archaeology.[2] She became an expert in xenoarchaeology, leading her to be hired by the Office of Naval Intelligence and stationed at multiple Forerunner research sites. When Installation 03 was discovered, she was one of the first people put on to the research team at Ivanoff Research Station. This would lead her to discover the Composer.[1]

Raid on Ivanoff Research Station[]

Main article: Raid on Ivanoff Research Station

When the Didact and Jul 'Mdama's Covenant fleet arrived at Ivanoff Station, they immediately began searching for the Composer. John-117 contacted the station and Sandra was the first to respond. She requested John's assistance in defending the station, but John wanted her to defend the Composer, until they arrived. After heavy fighting Cortana would tell her that they were on their way to her position, She would thank John and Cortana for the work that they had already done.[2]

Once John and Cortana had gotten to Sandra, she was panicked and confused, but took John-117 down to the Artifact's location and the rest of the station. John told Tilson that they are going to need to remove the Composer from the station so that the Didact couldn't get it. Tilson believed that it was not possible to relocate it to another position because of its immense size, and the time and effort it took to relocate it to the station. John then realizes that they need to destroy it. John told Sandra to continue evacuating her team while they dealt with the Composer. Tilson grieving about the loss of research tells John she'll prime the nukes so they can be detonated remotely. Once the station's exterior defenses came online, Tilson and her team broadcasted the final evacuation order and continued to rig the Nuke. She told John to meet them on the upper platform so they can get it to the Artifact.[2]

After the Didact took the Composer from the station, John found Tilson speaking with other scientists, he told her the Composer was gone, leaving her confused as to how it was taken. John tried to get Cortana to bring the station's defenses back online, but they weren't responding. As Tilson notices something is happening outside, the Didact fires the Composer, composing Doctor Tillson, as well as every organic being on board the installation, save for John-117. Using the Composer, the Didact composed them—destroying their bodies in a grotesque and most likely painful peeling back of the layers of the body, from skin to muscle to vital organs, to skeleton, and finally causing the entire body to disintegrate to a pile of ash.[2]

Remains of the data signatures that were extracted from these piles of ash, including that of Doctor Tillson, were collected by the Didact to create more Promethean Knights.[2]


She was very dedicated to her research, also caring greatly about her team, many of whom were killed in the initial Covenant attack against her station.




  1. On Twitter, she was reported as being born on Lodestone. However, the Halo 4 Visual Guide states that she was born on Coral.