The unspoken rule of Doctor Who is that the Doctor is nobody without their companions. Since the show's return in 2005, the Doctor has been accompanied by numerous friends and loved ones who've saved the day just as much as he has – and made audiences cry with their eventual departures.

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But first, they have to make their grand debut. It matters less where or when they're introduced than that they make a positive impression, winning over the hearts of both fans and the Doctor. As these IMDb scores indicate, these companions stand above the rest in Doctor Who's storied history.

"The Halloween Apocalypse" (Dan Lewis) – 7.1

Dan Lewis spreads his arms as a crowd gathers behind him in Doctor Who

Following the departure of Ryan and Graham, there's extra space on the TARDIS in "The Halloween Apocalypse."  The Doctor and Yaz meet Dan Lewis after he's kidnapped by Karvanista – who are intent on relocating humanity to protect them from the mysterious Flux – and soon welcome him into the chaos of their lifestyle in the pair's place.

A lot of season 13's opening episode is clunky and confusing, but Dan's introduction is definitely one of its highlights. He makes jokes at all the right times and has great chemistry with both Yaz and the Doctor. Also, a strong Liverpudlian identity is a rarity in television of this scale, but a great addition to a show as British as Doctor Who.

"Rose" (Rose Tyler) – 7.5

Rose Tyler looks sideways in her debut episode of Doctor Who in 2005

When Doctor Who returned in 2005, it made the bold move of focusing the first episode of its revival on the Doctor's new companion, Rose Tyler. From its opening seasons, it follows the emergence of the season's first villain – the Autons – through her eyes as someone who just happens to be in the wrong place at the wrong (or right) time.

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Because, of course, that's where she meets the Doctor. Their chemistry is strong from the get-go, and her humanity serves as the perfect foil for his mysterious, post-Time War angst. The episode's plot and action might be forgettable, bringing it down slightly in terms of overall performance, but it does a solid job of introducing one of the show's most beloved companions.

"The Runaway Bride" (Donna Noble) – 7.6

The Tenth Doctor and Catherine dressed as a bride in Doctor Who

Technically, Donna Noble made her first appearance in the closing moments of "Doomsday," but considering that episode is just dominated with the grief of Rose Tyler's exit it doesn't really count. Her real debut comes in the Christmas special "The Runaway Bride," where the Doctor works to stop the awakening of the Racnoss children at the heart of the earth.

The silliness of the plot lets it down a bit, but it's a lot of fun for a Christmas romp. Donna's brash, loud personality works strangely with the Doctor's more stoic demeanor. While he and Rose had romantic friction during her time in the TARDIS, his relationship with Donna is strictly platonic from the start. She may not have become a full-time companion until season 4, but this episode is enough to set them on track as one of the best Doctor Who duos the TARDIS has ever seen.

"The Pilot" (Bill Potts) – 7.9

Bill looking worried on a street at night in Doctor Who.

As the Impossible Girl, some fans believe Clara became too convoluted and unrelatable during her time in the TARDIS. Her successor, Bill, is the total opposite. She's warm, funny, and completely ordinary, working in a university canteen and gradually becoming embroiled in the Doctor's adventures after she starts attending his lectures on the sly.

The episode's plot (in which Bill's crush has become a fluid pilot for an alien entity) would be largely forgettable if it wasn't for the emotional stakes wrapped up in their relationship. What could have been a blossoming romance is cut short, leaving Bill – and audiences – heartbroken. Everything about her is so human, which is exactly what makes her so endearing as a companion.

"Smith And Jones" (Martha Jones) – 8.0

Replacing the first companion since Doctor Who's reboot was never going to be easy, but Martha more than holds her own in her debut. The London-based medical student is going about her daily life when the hospital she works in is teleported to the moon by the Judoon, who are trying to track down a prisoner.

Martha is sharp and perceptive, which ultimately leads to the hospital being safely returned to earth. It's clear from the start that she'll be an asset on the TARDIS – and it's also obvious that she has a romantic interest in the Doctor, who is still grieving Rose. Together, it's a strong opener for an interesting dynamic between the two, not to mention setting Martha up as a companion Doctor Who fans would still love to return today.

"The Husbands Of River Song" (Nardole) – 8.5

When the Doctor first meets Nardole, he's a servant of River Song who mistakes the Doctor as a surgeon she hired to attend to her dying husband, King Hydroflax. He's kind but bumbling, and clearly there for comic relief while the Doctor and River's relationship (and her failure to recognize his new regeneration) takes center stage.

Despite that, this appearance is enough to later solidify him as a companion for a whole season alongside Bill. He's the first alien companion the show's had since its revival, and the loss of River Song in this episode bonds him to the Doctor enough to become a loyal, trusted friend.

"Asylum Of The Daleks" (Clara Oswald) – 8.6

Clara looking surprised in Doctor Who

Confusingly, the Clara fans know doesn't actually appear until her third appearance in "The Bells of Saint John." But technically, "Asylum of the Daleks" is still her debut, as it features one of Clara's many shadow selves scattered throughout history by Clara herself to keep the Doctor safe.

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This version is Oswin Oswald, the survivor of a crashed starliner whose brain refuses to accept the fact she was converted into a Dalek. She's sweet, quirky, and funny (not to mention relentlessly flirtatious) from the off, and it doesn't take her long to fall into rapid rapport with the Doctor. Her story might end tragically, but it's enough to get fans hooked – especially when she breaks the fourth wall, turning to the camera and asking the Doctor to "remember."

"The Eleventh Hour" (Amy Pond) – 8.8

The Elventh Doctor and Amy Pond eating at a table in Doctor Who

Simultaneously introducing a new Doctor and a new companion is always tough. "The Eleventh Hour" does it best, following the Eleventh Doctor in the wake of his regeneration after he crash lands in the garden of a young Amy Pond.

The scenes between him and Amy as a child are pure magic, but the episode really kicks into gear when he leaves and accidentally returns 12 years too late. Now that she's a confident, headstrong young woman, the pair have to bond all over again as they try to capture Prisoner Zero and hand it over to the Atraxi. It's a unique set-up for a new companion, and it's obvious from just this episode that they have the makings of real best friends.

"The Empty Child" (Jack Harkness) – 9.2

He's never had a full season as a companion, but Jack Harkness is a regular fixture in the TARDIS. In season 1, the Time Agent and con man saves Rose while she's hanging over London at the height of the Blitz, and ends up helping save London from a threat he himself unwittingly caused.

Handsome, charismatic, and flirtatious, it doesn't take him long to win over Rose. He's a huge personality, and even the perpetually grumpy Ninth Doctor falls for his charms eventually. As Doctor Who's first televised LGBTQ+ companion, his debut in "The Empty Child" is a breath of fresh air.

"Silence In The Library" (River Song) – 9.4

River talks to Donna in Doctor Who

River Song is potentially the most complex companion the Doctor's ever had. Their timelines are never quite in sync, which means that the first time he meets her in "Silence in the Library" isn't the first time she's ever met him – it's just the first time she's met the Tenth Doctor.

Making her a complete mystery from her very first appearance is extremely in line with River Song as a character, and helps elevate an already mind-boggling episode. There's never any real explanation as to who she really is, just plenty of hints that she'll be important to the Doctor one day. However, considering how intelligent, confident, and worldly she is, it's pretty easy to see why he'll like her so much.

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