Caitlin "Kate" Todd is a fictional character featured in the CBS television drama NCIS portrayed by Sasha Alexander, appearing in 49 episodes of the series.

Following JAG's "Ice Queen" and "Meltdown", the character of Kate was created to replace that of Vivian Blackadder (Robyn Lively), who Donald P. Bellisario felt was "too soft".

[1][3] Co-star Michael Weatherly noted that he was not informed until February 2005, and only discovered Caitlin would be assassinated when he "saw the special-effects guy attaching a blood pack to [Sasha's] hair".

Chilean actress Cote de Pablo was later cast as Israeli Mossad Officer Ziva David[4] to replace the departed Alexander.

Caitlin was born in Indiana, and was the youngest of five children, including three brothers (whom she referred to as "practically psychotic"), and an elder sister (introduced as Rachel Cranston in Season 8 Episode 14 "A Man Walks Into a Bar..."), and was Catholic.

[8] Some time after college, she joined the United States Secret Service, and was eventually assigned to the President's security detail aboard Air Force One.

Kate first encounters Gibbs' team as a United States Secret Service special agent assigned to the Presidential Protection Detail on Air Force One.

During "Yankee White", Kate resigns from the Secret Service before her superiors fire her for disobeying the fraternization rules; NCIS Special Agent Leroy Jethro Gibbs recruits Todd almost immediately and assigns her to his team, pairing her with Anthony DiNozzo.

She was first taken aback by NCIS' apparent disregard for the rules and protested at times, yet she came to find herself ignoring guidelines in order to obtain key information.

Unlike Gibbs, Kate appears to get emotionally attached to victims as seen in the episodes "The Immortals" and "Left for Dead", during which she befriends a Jane Doe (Sherilyn Fenn) suffering memory loss after being buried alive.

[6] Similarly, Todd had an opportunity to kill Ari when he broke into the NCIS autopsy lab in "Bête Noire" and shot Gerald in the shoulder, but found she was unable to do so.

During the same episode, it was shown that she had drawn caricatures of the team, some of which showed DiNozzo lusting after a pretty girl, and NCIS forensic scientist Abby Sciuto as a bat.

After being officially relieved of the protection detail she had been assigned by Tom Morrow, Kate is shot in the head by sniper and Mossad double-agent Ari Haswari.

[17] During an imagined discussion with Dr. Donald "Ducky" Mallard in the morgue, Todd, who had been shot dead in the previous episode, explained that she had not been able to kill Ari because she had looked into his eyes and that there had been something kind in them.

She is laid to rest with civilian honors, after she is posthumously awarded the Presidential Medal of Freedom at the behest of Gibbs and Director Jennifer Shepherd.

[18] In "Probie" (S03E10), McGee states that unlike Todd, he had no previous law enforcement experience before enlisting as a NCIS Special Agent, while in "Bait" (S03E18) a teenage student held his classmates hostage inside a classroom by threatening them with a bomb strapped to his chest.

During "Truth or Consequences" (S07E01), Tony states that the third member of team Gibbs is deceased, and for the past four years that position has been filled by Ziva David.

In "Patriot Down" (S07E23), following the murder of SSA Lara Macy, Tony inquires as to who killed "another female NCIS agent", referencing Kate's passing.

Kate's sister, Dr Rachel Cranston, was introduced during "A Man Walks Into a Bar..." (S08E14), in which she was conducting mandatory psychological evaluation of the MCRT.

During "Life Before His Eyes" (S09E14), an alternate-universe version of Kate is shown in which she was never killed by Ari, is still an NCIS agent, and is married to DiNozzo with a baby girl named Kelly.

The goldfish is featured prominently until season thirteen's "Family First", and plays a significant role in "Whiskey Tango Foxtrot" (S11E01), when DiNozzo has a conversation with Kate regarding Ziva's absence.

[21] Confronted with Todd's death, a shocked and vengeful Gibbs found himself overwhelmed with guilt and, like the rest of the protagonists, began having visions of her.

He showed concern for her several times, including at the end of episodes "Left For Dead", when she realized she had been played by a victim, and "Bête Noire", when she was held hostage by Ari.

[30] In the episode "SWAK", after Todd was found to be uninfected, she continued to stay with DiNozzo, lying to him about her condition even though she knew that the risk of infection was still imminent.

As shown in the episodes "Kill Ari" I & II, DiNozzo struggled with sorrow, culminating in a scene in which he and McGee mourn over Todd's dead body in Dr. Mallard's autopsy room.

Typical to DiNozzo's chauvinistic personality, Todd appeared in the Catholic schoolgirl uniform that he had been asking about in the episode "Bikini Wax".

This "sexual fantasy" was portrayed after DiNozzo offered to go back out in the pouring rain and find the bullet that killed Todd and became upset when McGee improved the answer he had told to Gibbs.

[21] In the 200th episode, "Life Before His Eyes", one of several alternate reality scenarios featured Kate surviving, marrying DiNozzo, and having a child with him.

[34] As he does with other team members, Ducky would usually call Todd by her full name, Caitlin just like her future murderer, Ari Haswari did.