<Li> Halston Sage as Lieutenant Alara Kitan, the Orville's young Chief of Security . She is a member of the Xelayan race, which inhabits a high - gravity planet, giving her greater - than - human strength, allowing her to knock down doors and walls by charging against them, or crush a handheld cube of solid titanium and reshape it into a sphere with her bare hands . </Li> <Li> J. Lee as Lieutenant Commander John LaMarr . He is navigator of the Orville for most of the first season . He and Malloy strike up an immediate friendship in the first episode . Though intellectually gifted, he learned to hide his intelligence and settle for modest ambitions growing up . When Grayson discovers his high aptitude in "New Dimensions", she encourages him to fulfill his potential . As a result, he acquits himself so well during that episode's crisis that he replaces the outgoing Lt. Commander Newton as the Orville's Chief Engineer . </Li> <Li> Mark Jackson as Isaac, the Orville's Science and Engineering Officer . Isaac is a member of the artificial, non-biological race from Kaylon - 1 that views biological lifeforms, including humans, as inferior . Isaac explains to Mercer in the pilot that the Union's Admiralty offered a posting to any Kaylon willing to accept it, as an attempt to initiate relations between the two powers . Isaac accepted the offer because he saw it as a way to study human behavior . During the course of his time with the crew, he comes to observe and understand aspects of human behavior, such as sarcasm, slang, and practical jokes . Isaac perceives his surroundings with his body's internal sensors, and not with the two glowing blue "eyes" on his face, which are purely aesthetic . </Li> <Ul> <Li> Victor Garber as Admiral Halsey, Mercer's superior and an old friend of Grayson's father </Li> <Li> Chad Coleman as Klyden, Bortus' mate and father of their child </Li> <Li> Norm Macdonald as the voice of Lt. Yaphit, an amorphous, gelatinous, shapeshifting engineer on the Orville, who repeatedly attempts to obtain a date with Dr. Finn, and frequently flirts with other females on the ship . Despite telling her in "Cupid's Dagger" that he is in love with her, she does not reciprocate his attraction, but they become physically intimate in that episode after falling victim to a Retepsian sex pheromone . </Li> <Li> Larry Joe Campbell as Lieutenant Commander Steve Newton, Chief Engineer of the Orville until episode 1.11, when he leaves take a new job designing space stations, and is replaced by LaMarr </Li> <Li> Gavin Lee as Nurse Park </Li> <Li> Rachael MacFarlane as the voice of the Orville computer </Li> </Ul>

Who does the voice for isaac on the orville