Hailey Upton is a detective and sometimes second in command to Voight in the Intelligence Unit.

She has a dark past that occasionally affects how she approaches certain cases. She's often immersed in the action, whether it's shootouts, footchases, or car chases.

She's a decorated detective and considered one of the best on the unit.

Hailey had previously had a fling with Adam Ruzek before dating and eventually marrying her partner, Detective Jay Halstead, before he left not long after for another job.

Hailey has often found herself in life-and-death situations or immersed in some of the most controversial storylines tied to questionable police practices.