Nuka is the oldest son of Zira. He is considerably older than his two younger siblings, appearing first as a teenager while Vitani and Kovu are still cubs. Sometime in between the events of The Lion King and The Lion King II: Simba's Pride, he was banished to the Outlands alongside Zira and the rest of Scar's followers. Despite being the oldest of Zira's children, he is neglected by Zira in favor of Kovu, Scar's chosen heir.
Nuka is extremely mangy and is apparently infested with termites (partly due to living in a termite mound). Nuka has dark brown fur and a black mane, and keeps his front claws unsheathed, a trait seen in all the Outsiders. Judging from the thickness of his mane in his first appearance, he would be about a year and a half old. Despite being older than Kovu, his mane does not grow in as thickly - a trait seen in real lions, where stronger lions usually have thicker, fuller manes. It's hinted that because of the lack of food and water where he lives, he grew up weak, sickly and mangy to the point his mane couldn't grow like other lions. But that wasn't the case for Kovu as he grew up health, strong and a full mane.
Nuka is shown to be chicken-hearted, somewhat clueless and slightly neurotic. However, Nuka has an inflated opinion of himself, as he claims to be the strongest and the smartest. Considering his feelings of inadequacy and bitterness over his pride's favoritism towards Kovu however it is likely his egotism is in fact a defense mechanism to shield his insecurities and grant himself a sense of self worth. Nuka is shown to have a strong dislike and envy of his younger brother. He shows many similarities to Scar, having despising his brother for being chosen over him. He desires to please Zira, in order to get her attention, which eventually leads to his downfall. This makes him somewhat of a tragic figure as he is motivated by a longing for the praise and love Kovu receives from Zira more than anything else. In addition, its also implied that he has some mental and emotional instability, including pyromania, as evidenced by when, before proceeding to burn a large part of the Pride Lands to trick Simba into allowing Kovu into the pride as part of Zira's plan, he hollers "Woo! Fire!". Nuka also has a smart-alecky side, calling Kovu "The Chosen One" in a smart-mouthed manner when out of sight, and a wicked side to him cutting a branch Vitani is pulling only to give a wicked cackle when she falls backwards. At the end, Nuka gets the bravery to go after Simba himself, but it costs him his life.
Role in the film
In the film, a teenaged Nuka is shown at the home of the Outsiders, arguing with his younger sister, Vitani, over Kovu. Nuka has apparently left Kovu alone, despite being asked to baby-sit him, and it is implied that this happens often. Nuka expresses his jealousy over Kovu's position as Scar's chosen heir, as he was passed over despite being the oldest of Zira's children and Scar not being his father. He states his intention to tell his mother that he should be the heir, but quickly backs down after Zira returns and scolds him for not watching Kovu. Nuka watches as Zira makes a plan to have Kovu get close to Kiara so that Kovu can eventually kill Simba. When Zira lavishes a praising comparision of Kovu to Scar to the cub for his supposed brilliance Nuka groans in disgust only to be silenced by a growl from Zira and mutters bitterly, "Chosen one," as the two make their leave. Though Nuka likes the idea of killing Simba, he shows displeasure when Kovu's part in the plot is mentioned.
Nuka's next major appearance is as an adult, wandering the elephant graveyard with Vitani. The two have been tasked with setting a wildfire while Simba's daughter, Kiara, is out on her first hunt. He expresses revulsion at their surroundings denying Vitani's dismissal of his repulsion as fear. He is shown to continue to resent Kovu's position as a heir and his mother's favoritism towards him. Zira's plot is to have Kovu rescue Kiara from the fire, to allow Kovu to get close to Simba and kill him. The plan is successful, as Kovu saves Kiara from the wildfire, and is allowed to return to the Pride Lands. Nuka secretly follows the pride alongside his mother, in order to spy on Kovu. Whilst the two are watching Kovu's conversation with Kiara, Nuka furiously reacts when he makes no attempt to kill her but his mother hushes his protests noting that with Kovu and Kiara growing closer their goal of Simba's death is close to being reached.
When it appears that Kovu is beginning to have second thoughts about his role in Zira's plot, Nuka accompanies the Outsiders as part of an ambush, to try to kill Simba. As Zira orders the attack, Nuka is the first to tackle Simba, yet is swatted away. Simba is then cornered in a ravine and is forced to climb a log dam to escape. When Kovu refuses Zira's order to kill Simba, Nuka impulsively decides to do it himself, exclaiming, "I'll do it - for you, Mother! Mother, are you watching?! I'm doing it for you... and I'm doing it for me!"
However, while briefly grabbing Simba's ankle, Nuka slips and falls, ending up being crushed under several logs. Kovu rushes forward to dig him out, but is knocked aside by the frantic Zira, who finishes the job herself. Nuka succumbs to his injuries, after apologizing to his mother for his failure. Ironically, through his death, he finally gains his mother's attention and affection, and Zira blames Kovu for Nuka's death by slashing him across the face, which leaves him with a scar on his face.
The film draws parallels between the relationships of Scar and Mufasa and Nuka and Kovu. Scar became jealous of Mufasa's kingship and Simba's potential passage to the throne, which left him out of the direct succession. Nuka has similar feelings towards Kovu, but as he is less intelligent and more cowardly than Scar was, and also because he desires to gain his mother's approval, his jealousy comes across as more 'goofy' than evil.
In an original cut of the film, Nuka's death scene is extended. After Nuka, being crushed in the logs, says "I'm sorry, Mother. I tried." Zira manages to reach her paw to cradle his head gently. Pleased with Zira's affection towards him, Nuka says "Well, I finally got your attention, didn't I?" before he finally dies. Zira then asks Scar to watch over Nuka.
- Zira appears to love him as well as Kovu and Vitani, but was too focused on Kovu becoming Simba's murderer that she paid too less attention to him.
- According to some of the film's merchandise, Nuka was originally going to be shown as a cub.
- Despite that he was being listed as enemies, Nuka never met Nala, Timon, Pumbaa, Zazu, Rafiki and Kiara in the film at all.