This page contains information regarding Star Trek: Discovery, and thus may contain spoilers.
Eli was a sophisticated hologram who served as a medical officer at Federation Headquarters in 3189. (DIS: "Die Trying") According to Fleet Admiral Charles Vance, Eli's face was computer-generated and not based on any specific Human. (DIS: "There Is A Tide...")
In 3189, Eli treated a group of Kili refugees who had just hours to live. The USS Discovery crew, newly arrived in the future, determined that the Kili had consumed contaminated plants from the abandoned industrial planet Urna. The ship retrieved uncontaminated seeds from the USS Tikhov and Dr. Hugh Culber fomrulated the antidote to treat the Kili.
Eli's primary diagnostic scanners were capable of detecting "anomalies as small as aberrant protein coding in your neurons," meaning he could act as an effective lie detector. (DIS: "Die Trying") That capability was often used in high-level negotiations, as when in 3189 Eli sat in on talks between Vance and Osyraa. Though he largely confirmed Osyraa's intentions as genuine, Eli warned Vance that her promise to appoint an ambassador free from her influence was a lie, which Osyraa insisted was a glitch. (DIS: "There Is A Tide...")