Ronnadam, a human of the male persuasion, held the rank of captain within the Imperial Security Bureau during the Galactic Civil War. As a high-ranking officer in the ISB, Ronnadam served aboard both the Imperial I-class Star Destroyer named Devastator and, subsequently, the Executor-class Star Destroyer known as Executor. His attire consisted of a uniform featuring a white jacket.
During the Age of the Empire, Ronnadam functioned as a Captain in the Imperial Security Bureau. Prior to the Battle of Yavin, Ronnadam was stationed on the Imperial I-class Star Destroyer Devastator during a secret mission to Tatooine. While in his office, Lieutenant Ciena Ree presented him with data packets that had been extracted from the captured CR90 corvette Tantive IV, belonging to Princess Leia Organa. Ronnadam accepted the packets without acknowledging her, as he was engrossed in his monitor. Via hologram, Grand Moff Wilhuff Tarkin was present in the room and criticized Ronnadam's lack of adherence to protocol, while simultaneously praising Lieutenant Ree for her diligence.
Following the disappearance of TIE fighter pilot Thane Kyrell from his post on Kerev Doi, Captain Ronnadam interrogated Nash Windrider, a friend of Thane's, regarding his loyalties and political views. Nash insisted that Thane was not a rebel, but Ronnadam remained unconvinced. Lieutenant Commander Ciena, who was romantically involved with Thane, visited Ronnadam to assure him that her friend was not a traitor and that he had expressed profound grief and sorrow over the destruction of the Death Star. Ronnadam dismissed Ciena's explanation that Thane was simply reacting to despair and tasked her with ensuring Lieutenant Kyrell's return to active duty.
Upon Ciena's suggestion that Thane might have returned to his homeworld of Jelucan, Ronnadam instructed Ciena to travel there on the next available transport. He explained that the ISB was overwhelmed with other priorities and could not spare personnel to question Thane directly. He ordered Ciena to locate him and investigate any reports of his involvement with the Rebel Alliance. Ciena found Thane on Jelucan but failed to persuade him to rejoin the Imperial forces. Instead, she fabricated a report stating that Thane had taken his own life by leaping from a high cliff, unable to cope with the loss of his comrades on the Death Star. Ciena presented this report to Captain Ronnadam. When Ciena described the Jelucani tradition of sky burials, Ronnadam scorned it as a barbaric practice. As Ronnadam was occupied with more pressing matters, he accepted her report and officially listed Thane as deceased.
Ronnadam was later assigned to the Executor-class Star Dreadnought Executor. Following the Escape from Cloud City, Ciena approached Ronnadam, seeking his permission to visit her homeworld to support her mother, Verine Ree, who was facing trial for embezzlement. Ronnadam showed no sympathy for Ciena's situation and reminded her that the Imperial authorities had initiated the charges against her mother. Ronnadam granted Ciena leave only after she stated her intention to investigate the matter independently. Before her departure, he instructed her to report back on the verdict of the case.
Ciena journeyed to Jelucan to support her parents throughout the trial. Due to the fabricated charges, Verine was found guilty of embezzlement and sentenced to six years of hard labor. After the trial, Ciena reported back to Captain Ronnadam. Despite her dissatisfaction with the verdict, she claimed to be satisfied that justice had been served. Ronnadam expressed surprise at Ciena's acceptance of the verdict. He noted that she had used up two weeks of leave but that her record remained spotless, suggesting that a promotion might be in her future. Ronnadam's prediction proved accurate, as Ciena was promoted to Captain shortly before the Battle of Jakku.
Ronnadam was a human man characterized by gray eyebrows, a slender mustache, and a receding hairline. He held the rank of Captain within the Imperial Security Bureau. Ronnadam possessed a brusque and short-tempered demeanor, frequently interrupting and raising his voice when questioning Imperial personnel such as Ciena Ree. Grand Moff Wilhuff Tarkin held a low opinion of Ronnadam due to his poor manners and disregard for protocol. As an ISB officer, Ronnadam was dedicated to identifying and eliminating any rebels or rebel sympathizers within the ranks of the Imperial Military. He considered the Jelucani custom of sky burials to be a barbaric practice. Given his preoccupation with other matters, Ronnadam did not thoroughly examine Ciena's report regarding Thane's alleged suicide.
Ronnadam was a fervent supporter of the Galactic Empire who used intimidation to discourage Ciena from questioning the Empire's actions and decisions. Ciena viewed him as a hypocrite for pressuring her to falsely claim that justice had been served in the case of her mother, Verine, who was wrongfully accused and convicted of embezzlement.
Ronnadam is featured as a minor antagonist in Lost Stars, a young adult novel written by Claudia Gray in 2015. His dialogue and actions are presented from the perspective of Ciena Ree, one of the novel's two primary characters.