<P> The Orville is set on the titular U.S.S. Orville (ECV - 197), a mid-level exploratory space vessel in service to the Planetary Union, a 25th - century interstellar state encompassing Earth and many other worlds . </P> <Ul> <Li> Seth MacFarlane as Ed Mercer, the captain of the Orville . Mercer was an up - and - coming officer, believed to be on the fast track to commanding his own heavy cruiser by age 40 . However, a year before the pilot, he caught his wife Kelly in bed with an alien . Since then, he was cited for becoming lax in his duties, including six instances of reporting to duty while hungover, but was informed that due to the size of the fleet and the retirement of the former captain, the Orville, a mid-level exploratory ship, was in need of a new commanding officer . </Li> <Li> Adrianne Palicki as Commander Kelly Grayson, the first officer of the Orville and Ed Mercer's ex-wife . The two divorced when Mercer caught Grayson in bed with an alien . Unbeknownst to Mercer, Grayson personally went to Admiral Halsey to plead her case to give her ex-husband a command, stating that despite some personal setbacks, he deserved his own command . She asked Halsey to keep that from him when assigned the Orville . Mercer and Grayson decide to put their differences aside, to work together as a team and stay as friends . </Li> <Li> Penny Johnson Jerald as Doctor Claire Finn, the Chief Medical Officer on the Orville, holding the rank of Lieutenant Commander . A physician of exceptional credentials, she has expertise in molecular surgery, DNA engineering and psychiatry, which could have afforded her the privilege of serving on the heavy cruiser of her choice . She instead chose the mid-level exploratory vessel because, as she explains to Mercer in the pilot, she prefers to request her transfers based on where she feels she is needed, as she feels more stimulated by such assignments . When she tells Mercer she felt he could use her help on his first command, he interprets this as lack of confidence on her part in his competence, though she denies this . Having never found the ideal opportunity to marry, she chose to become a single mother, and her two sons, Marcus and Ty, travel aboard the Orville with her . </Li> <Li> Scott Grimes as Lieutenant Gordon Malloy, the helmsman of the Orville and Mercer's best friend . Considered the best helmsman in the fleet, he was relegated to desk duty after an attempt to impress a girl resulted in him shearing the door off a cargo bay during a precarious shuttle docking, losing cargo in the process . He was specifically requested by Mercer despite some hesitation by Admiral Halsey, who harbors concern over Malloy's history of crude and juvenile pranks . </Li> <Li> Peter Macon as Lieutenant Commander Bortus, the second officer aboard the U.S.S. Orville . Bortus is from Moclus, a planet whose primary industry is weapons manufacturing, and whose inhabitants, the Moclans, are a single - gender species . Bortus exhibits a degree of stoic formality . For example, Bortus disapproves of the bridge crew discussing Mercer and Grayson's breakup after Mercer leaves the bridge in the pilot episode . Among the peculiarities of the Moclans are that they only urinate once a year . Moclans reproduce through the laying of eggs, which are incubated for 21 days . Bortus and his mate, Klyden, become parents in the series' second episode, when Bortus incubates and hatches an egg . When the child is revealed to be female, a rare occurrence among Moclans, Bortus and Klyden's desire to have her undergo sex reassignment surgery provides the allegorical conflict of the series' third episode . </Li> <Li> Halston Sage as Lieutenant Alara Kitan, the Orville's 23 - year - old 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 John LaMarr, the navigator of the Orville . He and Malloy strike up an immediate friendship in the pilot, based on their ironic view that they are both "jerks". </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> Seth MacFarlane as Ed Mercer, the captain of the Orville . Mercer was an up - and - coming officer, believed to be on the fast track to commanding his own heavy cruiser by age 40 . However, a year before the pilot, he caught his wife Kelly in bed with an alien . Since then, he was cited for becoming lax in his duties, including six instances of reporting to duty while hungover, but was informed that due to the size of the fleet and the retirement of the former captain, the Orville, a mid-level exploratory ship, was in need of a new commanding officer . </Li> <Li> Adrianne Palicki as Commander Kelly Grayson, the first officer of the Orville and Ed Mercer's ex-wife . The two divorced when Mercer caught Grayson in bed with an alien . Unbeknownst to Mercer, Grayson personally went to Admiral Halsey to plead her case to give her ex-husband a command, stating that despite some personal setbacks, he deserved his own command . She asked Halsey to keep that from him when assigned the Orville . Mercer and Grayson decide to put their differences aside, to work together as a team and stay as friends . </Li>

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