Tie

A tie was an article of clothing commonly associated with men's apparel on the planet Earth. Ties were worn for their style value, but could also signal levels of formality, association with particular schools, companies, or other groups. A tie was also favoured by the Doctor in most of his incarnations.

The Eleventh Doctor often wore bowties, which he stated were "cool" on many occasions.

While in Perivale in 1883 at Gabriel Chase the Seventh Doctor deflected anticipated criticism from Ernest Matthews by saying, "Let me guess. My theories appall you, my heresies outrage you, I never answer letters, and you don't like my tie!" (DW: Ghost Light)

On Vortis, the First Doctor used a Coal Hill School tie belonging to Ian Chesterton to test an unknown liquid, finding it to be acid. Ian was momentarily more concerned about the loss of his tie than the fact that his life had just been saved. (DW: The Web Planet)

In 1930, when he was aboard the R101 airship the Eighth Doctor was denied access to an area of the R101, he protested, "I'm wearing a tie!" (BFA: Storm Warning)

In 2008, before they had met from her perspective, the Doctor got Martha Jones' attention in the street and dramatically took off his tie. He did this after they had met and experienced the story's events in his timeline, but before this in hers, as a "cheap trick" to prove he was telling the truth. (DW: Smith and Jones)

Following his regeneration and recovery in 2008 the Eleventh Doctor frequently proclaimed that "bow ties are cool". (DW: The Eleventh Hour) He continued to proclaim this on several occasions despite Amy Pond's belief they were not. (DW: Amy's Choice, Vincent and the Doctor, The Lodger, The Big Bang) While on Demons Run, the Eleventh Doctor once again defended the belief that "bow ties are cool" upon meeting the ganger of Melody Pond. (DW: A Good Man Goes to War)

On both his visits to the Musée d'Orsay in 2010 the Eleventh Doctor complimented Dr. Black, on his choice of tie. (DW: Vincent and the Doctor)

The Doctor used his bow tie in a handfasting when he married River Song. (DW: The Wedding of River Song)

The Doctor's ties

In most, though not all of the Doctor's incarnation he wore a tie of some form during some of his regeneration's life.

The First Doctor almost always wore a wing collar with a bow tie, which took the form of a long, oblong piece of cloth tied in a large bow. It was almost always dark in colour, but on one occasion he wore a tie that had a black-and-white checked pattern. (DW: The Rescue)
The Second Doctor typically wore a small, pre-tied bow tie. He attached it to his shirt with a safety pin. It performed the function of closing the top of his shirt, in place of a collar button.^{[source needed]}
The Third Doctor occasionally wore ties, favouring large, velvet butterfly-style bow ties to go with his distinctive velvet smoking jackets.^{[source needed]}
The Fourth Doctor sometimes wore a four-in-hand knot tie, but also often went tieless or wore a loose cravat or scarf.^{[source needed]}
The Sixth Doctor wore long bow ties in a loose knot in the style of the First Doctor, but his became wider at the ends with diagonal edges. Rather than being plain, they were either bright blue or red with polka dots, or yellow with a starfield pattern. (DW: Terror of the Vervoids)

Seventh Doctor's tie. (NA: Original Sin])

Early in his regeneration the Seventh Doctor wore wore a four-in-hand tie in a paisley pattern. (DW: Time and the Rani) Whilst later in his regeneration he wore a four-in-hand tie with a white suit. (NA: Original Sin)
The Eighth Doctor typically adopted a silky cravat, starting with the Wild Bill Hickok costume that he appropriated shortly after regeneration. (DW: Doctor Who (1996))
The Tenth Doctor usually wore four-in-hand ties of various patterns with his suits, but he also went open-collared sometimes. On formal occasions, such as the presentation by Lazarus Laboratories or the party on the Titanic, he wore a bow tie. (DW: The Lazarus Experiment, Voyage of the Damned)
The Eleventh Doctor wore pre-tied red and blue bow ties. He also wore a white one to Rory and Amy's wedding and when he was dying after being poisoned by Melody Pond. (DW: The Big Bang)

Others' ties

Ian Chesterton often wore a four-in-hand tie while travelling with the Doctor.
Vislor Turlough continued to wear his Brendon Public School uniform, complete with school tie and wing collar, through most of his travels with the Doctor.
The Silence wore four-in-hand ties along with their suits. (DW: The Impossible Astronaut)