In 2267, on stardate 2821, Kelowitz was the leader of landing party number two, responsible for searching for the missing shuttlecraft Galileo, which had crashed on the planet Taurus II. His party was ambushed by the planet's inhabitants, resulting in one dead and two injured. He was later treated for his injuries in the sickbay. (TOS: "The Galileo Seven")
Later that year, on stardate 3045, Kelowitz was one of three tactical aides, including O'Herlihy and Lang, who beamed to the Earth observation outpost on Cestus III. Upon arriving, they discovered the colony had been destroyed by the Gorn, a previously unknown species. Upon the discovery of the Gorn's position Captain Kirk ordered Kelowitz and Lang to "flank out [and] [l]ay down fire on coordinates Mr. Spock gave you. Even if you don't see them. Keep your heads down." After reporting the death of Lang to Kirk, Kirk requested a tactical evaluation from Kelowitz of the location of the Gorn who had them pinned down. Kelowitz figured they were on the high ground and calculated, for Kirk to launch a photon grenade, that they were at a distance of "twelve hundred yards, azimuth eighty seven," noting that it was "pretty close for one of these little jewels." By the time the Enterprise was able to retrieve the landing party, he was the only one of the three aides who survived the mission. (TOS: "Arena")
Kelowitz was part of the landing party to Omicron Ceti III on stardate 3417, and he was paired with Lieutenant Hikaru Sulu in investigating the mysterious colony there. It was Kelowitz who first noticed there were no animals on the planet. Later, he was taken over by alien spores, though the spores were eventually destroyed by a subsonic transmitter, and he was released of their control. (TOS: "This Side of Paradise")
|Tactical officers of the starships Enterprise|
|Enterprise NX-01:||Alex • Billy • Reed • Unnamed • Greer|
|USS Enterprise:||Kelowitz • Lang • O'Herlihy • Chekov (post refit)|
|USS Enterprise-D:||Armstrong • Bailey • Barnaby • Burke • Hayes • Kellogg • McDowell • Rainer • Smith • Taitt • Torigan • Williams • Worf • Yar • Unnamed • Crusher • Gaines|
|USS Enterprise-E:||Armstrong • Daniels • Kelly • Worf|
|ISS Enterprise NX-01:||Reed • Unnamed|
Kelowitz was played by Grant Woods.
In the cast list from the final draft script of "The Galileo Seven", Kelowitz was referred to as a lieutenant commander. In the script's stage directions, he was described thus; "Kelowitz is a young, soldierly appearing man. His face is dirty, his uniform torn. There is a small scratch on his face."
As evidenced by the final draft script of "Arena", this character's role in that episode was at one point intended to have been filled by a new character named Molton, who the script described as a "tactics officer". Likewise, in the script for "This Side of Paradise," the role Kelowitz fills was written for one Crewman Dimont.  When Grant Woods was cast in these roles, the characters were renamed to keep continuity with his previous appearance.