Alternate Reality(split 2233)
Co-Co's species was a type of humanoid with large eyes and a head ridge.
Several members of this alien species were present on Starbase Yorktown in 2263, including two separate females (one of whom wore an operations division Starfleet uniform who were each walking with a friend through an exterior thoroughfare in the starbase while the USS Enterprise made its way into the facility.
Wearing a different outfit, one of these aliens, Co-Co, later attended James T. Kirk's thirtieth birthday party, indoors at the starbase. (Star Trek Beyond)
Although these aliens were unnamed on-screen, a behind-the-scenes source has linked at least one of them (i.e., the one attending Kirk's birthday party) to the name "Co-Co".