Spoiler warning: Plot and/or ending details follow.
Lieutenant Evan Connolly was a human man, a Federation Starfleet officer in the 23rd century. In 2257, he served as chief science officer of the USS Enterprise under the command of Captain Christopher Pike, taking over for Lieutenant Spock while the latter was on an extended leave of absence.
Along with Pike and Commander Nhan, Connolly beamed aboard the USS Discovery after the Enterprise suffered a catastrophic malfunction. Along with Pike, Nhan and Commander Michael Burnham, Discovery's chief science officer, Connolly investigated the wreckage of the USS Hiawatha but was killed during the mission. (DSC episode: "Brother")