In addition to performing autopsies on the victims, Ducky composes a psychological profile on any potential suspects or criminals that the team encounter, having graduated after taking a forensic psychology course.
His current assistant is James Palmer who became the permanent replacement for Ducky's previous assistant, Gerald Jackson who temporarily resigned after he was held hostage and shot in the arm by terrorist Ari Haswari in the Season 1 episode, Bête Noire (episode) and who later resigned from NCIS for good after Ari captured Gerald yet again in the Season 3 episode, Kill Ari Part 2 (episode).
Born in Scotland to Victoria Mallard and an unnamed man, Ducky grew up in Scotland.
He was educated at Eton College, and subsequently graduated from University of Edinburgh's Medical School. He also attended Kings College, Cambridge for a year before leaving to go to medical school he started to study English Language and History.
Before joining NCIS, Ducky also worked with several other organizations including the British police before coming to the US and joining NCIS.
Ducky by his own volition affirmed that he served in the military during the Vietnam War although whether he served in the American military is unknown.
Ducky also served as an officer in "The Regiment", implying he served in the British SAS.
In 1980, Ducky worked in a refugee camp in Afghanistan and while there, he became acquainted with Polish born CIA interrogator, Marcin Jerek who was known locally as "Mr. Pain."
As a result of this acquaintance Ducky was later mistakenly charged with war crimes for violating Article Four of the 1949 Geneva Conventions by the government of Afghanistan.
When the truth surrounding the events was revealed through the efforts of Gibbs and the team who arranged a meeting between Jerek.
During Ducky's confrontation with Jerek it was revealed that Jerek was trying to break Ducky whose status a doctor was a beacon of hope for the refugees. Jerek tortured an innocent man who would then be sent to Ducky for medical care.
Under stress Ducky eventually made the decision to end the young man's suffering by giving him an overdose of morphine which apparently caused his death, a decision which would haunt Ducky for years.
After Afghianstan, Ducky joined NCIS and became the Medical Examiner, replacing Dr. Walter Magnus.
JAG Season 8
He helped the NCIS team investigate the death of a Lieutenant whose body was found in a park and also personally performed the autopsy on the remains which were revealed to be to those of JAG Lieutenant Loren Singer.
NCIS Season 1
NCIS Season 2
NCIS Season 3
In Kill Ari Part 1 (episode), Ducky like the rest of the team struggled to come to terms with Kate's death.
Ducky also personally oversaw Kate's autopsy, refusing to bring in another Medical Examiner, not someone like Kate.
In Hiatus Part 1 (episode), when Gibbs was injured and left comatose after being caught in an explosion on board a Turkish ship, Ducky stayed by Gibbs's bedside.
NCIS Season 4
NCIS Season 5
NCIS Season 6
In the Season 6 finale episode, Aliyah (episode), Ducky performed the autopsy of Mossad Officer Michael Rivkin who had died from injuries sustained in his fight against DiNozzo before the remains were later released and returned to Tel Aviv, Israel so that they could be given a proper burial.
NCIS Season 7
A month before Double Identity (episode), Ducky's mother passed away. Ducky put her house on the market for sale, and began the process of buying a historic brownstone in Georgetown. He also ensured that her beloved Corgis were adopted by a loving family.
NCIS Season 8
NCIS Season 9
In the last few seconds of the Season 9 finale episode, Till Death Do Us Part (episode), while walking on a beach near the site of Palmer's wedding which was taking place in Miami, Ducky received word of the Navy Yard Bombing and later collapsed due to a heart attack brought on the shock of the news.
NCIS Season 10
In the Season 10 premiere episode, Extreme Prejudice (episode), Ducky was seen in a hospital bed, Palmer having managed to find and save Ducky from certain death.
NCIS Season 11
NCIS Season 12
NCIS: New Orleans Season 1
Ducky appeared in the NCIS: New Orleans Season 1 premiere episode, "Musician Heal Thyself".
When he was first introduced in the two pilot episodes for NCIS, Ice Queen (episode) and Meltdown (episode), Ducky was something of a dirty old man, regularly hitting on fellow colleague Vivian Blackadder as he attempted to ask her out to dinner but Viv always turned him down, stating that she never went out with men old enough to be her father.
Ducky's nickname comes from 2 factors. One from his first name, Donald, the same as the well loved character from Disney, the duck "Donald Duck." Also, his last name is Mallard, which is a certain breed of duck.
However, when NCIS went solo, Ducky had stopped hitting on his colleagues and became more mature, developing a habit of talking to the corpses, a trait which had disgusted Blackadder who had also claimed that Ducky had a lack of respect for the dead.
In the main NCIS series, Ducky's dirty behavior has disappeared or some extent been passed on to both DiNozzo and Palmer.
In addition to being dedicated to his work, Ducky has a tendency to often change subjects and ramble on about a possible story much to Gibbs's irk.
A man in his seventies or eighties, Ducky is a man with short brown hair and blue eyes.
He often wears business suits and bowties as well.
Whenever he's in the field, Ducky is seen wearing a coat that states "NCIS Medical Examiner. Dr. D. Mallard".
As NCIS's Medical Examiner, Ducky is skilled at performing autopsies on the many victims that he examines with his findings often determining if the victim died of natural causes or if they were murdered.
Ducky also has a Psychological degree, enabling him to perform and create psychological profiles to determine the mindset of the suspects that the NCIS team are currently after which has often come in handy.
Ducky's specialty is performing autopsies with his results often helping the NCIS team pursue other lines of investigation with Ducky himself often determining if the death of a United States Marine Corps or Navy officer was natural or murder.
Having earned a Masters Degree in psychological profiling, Ducky is now capable of creating profiles in which will describe the suspect that the main NCIS team are searching for.
Despite being a Medical Examiner, Ducky's medical skills have often in great use to members of the NCIS team as he has often treated injuries that the NCIS team have often received.
Leroy Jethro Gibbs
Ducky and Gibbs have a longstanding friendship that dates back to the period when Jethro and Jenny Shepard were partners in France, because he and Jethro escaped in a boat procured by Jenny. Ducky's friendship with Jethro was further reinforced when after Gibbs returned to NCIS after coming out of semi-retirement, he apologized to Ducky for his actions after he came out of the coma.
Also during "Hiatus" Gibbs was in a coma he was the only one there when he awoke. In that same episode, DiNozzo commented that if Gibbs didn't remember Ducky he wouldn't remember anyone.
Additionally, Ducky is one of the few people who regularly calls Gibbs "Jethro" apart from former NCIS Director Jennifer Shepard, FBI agent Tobias Fornell and G. Callen, a agent with the NCIS Office of Special Projects in Los Angeles.
Ducky's relationship with Viv could almost be considered fatherly except for the fact that Ducky kept regularly hitting on Viv and even went so far as attempt to invite her to dinner, a request Viv constantly denied.
Viv also expressed some disgust at Ducky's habit of talking to the dead, believing that Ducky had a lack of respect for the dead.
After Kate joined the team, Ducky developed something of a fatherly attitude towards her. The two later developed great respect and had a good relationship and Ducky even preferred to call Kate "Caitlin" instead of "Kate".
When Kate's remains were brought back to NCIS after her death at the hands of Ari Haswari in the Season 2 finale episode, Twilight (episode), Ducky was seen standing in the darkened morgue before unzipping the body bag containing Kate's remains and Ducky then commented seconds to Kate's body that he was so sorry.
Like the other members of the team, Ducky too had a vision of her talking to him and she told him that she should have killed Ari while also voicing a belief that she did not deserve to die.
When Gibbs later confronted him, telling Ducky that he should have had another Medical Examiner perform the autopsy, Ducky stated that he couldn't, not for Kate.
Donald and Ziva have a very good relationship, most likely because she saved his life when the two were being held hostage by Elaine Burns in "Silver War".
He refers to her as his friend in 'Good cop, Bad Cop' and shows concern over her mental state during the 2nd, 3rd and 4th episodes of Season Seven. They drink tea together in 'Witch Hunt'.
They both comment on Tony's bad English in 'About Face,' as Ziva's English is closer to "Queen's English" (English spoken in Britain), which Ducky would speak.
They have a very good friendship, this is seen in numerous episodes where they joke and laugh and comfort each other. They also seem to have friendship due to the common bond of their profession. He is also the only person to call her by her full first name Abigail although Abby has expressed dismay at being called that.
Ducky's relationship with Jimmy is akin to the relationship that exists between a father and a son. In this way Ducky's and Jimmy's relationship parallels the relationship between Gibbs and DiNozzo, with the elder mentoring the younger: Ducky through his stories, and Gibbs through his rules. Jimmy is one of few people close to him that calls him "Dr. Mallard" instead of "Ducky" and by the same token Ducky usually addresses Jimmy as "Mr. Palmer"; however, Ducky has been known to call Jimmy by his full name when concerned for him.
There is a bit running gag where they are usually late to a crime scene due to Jimmy's driving and his tendency to get lost, much to Ducky's fustration. To a certain extent Jimmy has developing Ducky's trait of storytelling while working on cases, as demonstrated in episode 6.20 ("Dead Reckoning") when Jimmy and Ducky engage in a discussion about harmony.
Like Kate Todd and Ziva David, Ducky has taken a liking to Bishop with the relationship between them friendly as Ducky sees Bishop as a surrogate daughter of some sort.
Ducky also calls Bishop by her first name, "Eleanor".
At some point in the past Dr. Mallard had a brief liaison with Agent Sharp. Mrs. Mallard disliked Agent Sharp although, the reason for her dislike is not elaborated upon. It was also noted by Sharp that her husband hated Ducky and Ducky confirms that he hated him too. Ducky called the affair 'one moment of weakness'.
Unlike most Medical Examiners, Ducky often talks to his corpses to counteract the rudeness of him exploring their remains to determine how they died.
He prefers not to call them bodies, instead choosing to refer them to as his "guests".
- Ducky is the first ever main character of the NCIS team to have been been featured in a Foof when it was introduced in the Season 2 episode, Lt. Jane Doe (episode).
- David McCallum is best known by many fans for his work in the 1960s series, "The Man from UNCLE".
- Ducky's car of choice is a Vintage Morgan which was revealed in the Season 3 premiere episode, Kill Ari Part 1 (episode).