Commander T'Illups was a hybrid individual resulting from the symbiogenetic merging of T'Ana and Andy Billups. They were created accidentally in 2381 when a petal from a symbiogenetic alien orchid landed, unnoticed, on Billups' foot as he and T'Ana beamed from the USS Voyager to the USS Cerritos. T'Illups possessed T'Ana's assertiveness and medical expertise, along with Billups' engineering acumen.
Upon learning that Captain Kathryn Janeway's solution to the precedent of Tuvix was to murder him by separating his genome, Captain Carol Freeman decided instead to bring T'Illups to Earth in the hopes that Starfleet could provide an alternative. However, T'Illups had also learned of Tuvix's fate, and resolved to escape it by creating allies. After luring Doctor Migleemo to their quarters, T'Illups arranged to merge him and Freeman into another hybrid, whom they dubbed Frigleeman.
T'Illups proceeded to order the creation of Shabarnes, Swhale Swhalens, and Chondus, intending to transform the entire Cerritos crew into a "Tuvix army". As they were combining Lieutenant Westlake and Ensign Jennifer Sh'reyan, all six hybrids were beamed into the brig by Ensign T'Lyn. However, since they were carrying samples of the orchid, they re-materialized as a single non-sentient amalgamation.
With the aid of the tricorder T'lllups modified, the ensigns were able to separate the beings to their original individual forms. (LD: "Twovix")
T'Illups was voiced by Nolan North.