The 4th Doctor: Bohemian, irresistsable grin, Zoanon, the original mad man, the Scarf God, the iconic one. His debut came in prematurely at first, but the timing was right once he regenerated at UNIT HQ before the very eyes of Sarah Jane Smith and Brigadier Lethbridge-Stewart. Recoperated from delirium while in the care of medical officer Lt. Harry Sullivan, the Doctor tried to take off in the ship after trying him up and putting him in the cabinet. He was talked out of it by the Brigadier when he asked for his assistance on the investigation of Think Tank and Professor Kettlewell's K1 robot that eventually ran amuck. This incarnation wore a brown fedora, a very long multi-colored scarf and a red corduroy jacket; later a variety of coats. With the robot destoryed, the Doctor and Sarah took off in the TARDIS with Harry along for the ride.
With the ship finally back, the trio resumed their travels which included 24th Century Prague, the planets, Peugross, Aquatica, and Diamedes. The TARDIS returned to Earth where they and UNIT took on the Zygons who plot to use the Loch Ness Monster and their scheme. It was immediately after this event that Harry decided to stay behind leaving only the Doctor and Sarah Jane to go on. Harry would eventually see the Doctor again (albeit 23 years later) when he encountered the Voracians on two occasions and before then the Kraals
As time went on, the Doctor and Sarah Jane encounter aditional being along the way. Among them, a planet
with anti-matter monsters, the Osirian god Sutekh, the infamous Morbius (plus the Sisterhood of Karn), the Pescatons, the Krynoids, and the Mandragora Helix. In one account, the Doctor and Sarah Jane encounter Iris Wildthyme in England, 1764. When the TARDIS landed in a quarry, Sarah Jane was nearly caught in a explosion when she found a petrified hand and was posessed by Eldrad. Under Eldrad's influence, Sarah Jane took the hand to a nuclear station where it regenerated into a woman. Granting Eldrad's request, the Doctor took her/him back to Kastria to be restored to his male form. Upon finding out he was responsible for the planets's demise, Eldrad was tripped into a pit; falling to his doom. Aggravated by all the times she was nearly injured, hypnotized and the lot, Sarah Jane announced to the Doctor that she wantes to go home. At the same time, the Doctor recieved a message from the Time Lords to return to Gallifrey and leave her behind. He dropped Sarah Jane off only to be revealed by her decades later that he actually dropped her off at Aberdeen rather than South Croyden.
Upon his arrival on Gallifrey, the Doctor was unsuccessful in preventing the Lord President's assassination, automatically making him a murder suspect. He was able to stay his execution by announcing his candidacy while looking for the real culprit. The culprit turned out to be the now degenerated Master. It was this adventure that reignited his bemusement of Time Lord decadance. It was revealed later that he was still eligable to become Lord President as he was the last candidate standing. After leaving Gallifrey, the Doctor resumed his travels alone. While on a unknown planet, the Doctor encountered a colony ship computer called Xoanon. Upon repairing the computer, he accidentally left an imprint of his mind into it triggering multiple personalities and the results that followed many years later. When he returned to the planet, the Sevateem (descendants of the Mordee expedition's survey team) viewed him as their evil god. With the aid of the female Sevateem tribal named Leela, the computer was cured and upon leaving she hopped into the TARDIS; much to the Doctor's shock and bemusement. The two made their first trip to a 23rd Century sandminer from Kaldor City where they stumbled upon a multiple murders caused by one of the ship's crewmembers who want the sandminer robots to revolt. In his quest to educate his new savage friend, the Doctor took her to various location in Earth's history. The first was in Victorian England where they encountered Li H'sen Chang and his master, the mysterious Weng Chang (who in reality was the 51st century criminal Magnus Greel). Aiding the duo in stopping Greel's malfunctioned time machine from destroying reality was Palace Theatre owner Henry Gordon Jago and pathologist George Litefoot; the two men would go on to become amatuer sleuths solving mysteries of the paranormal and/or alien phenomena.
The Doctor continued to educate Leela further in the adventures. Among them was the Space Station Nerva, Moravanian Museum on Moravania Minor, Roman Britain 60 AD, 2015 (where the Daleks were present), going up against the Master and the Kraals and Mt. McKerry, St Alban where the duo encounter the wild Stormcrow. While in a lighthouse in the 20th Century, the Doctor and Leela discover a Rutan who was using the planet as a strategic placement in the species war against the Sontarans. After destroying the alien via explosives (destroying the Lighthouse in the process), Leela's eyes changed from brown to blue when watching the explosion. The duo traveled to the Bi-Al Foundation in the year 5000 where the host of the Nucleus took hold of the Doctor's body as well as others. With the aid of Leela, Professor Marinus and his robotic dog K9, the Doctor defeated the Swarm and their host. Marinus gave K9 to the duo as a gift; they both became very fond of the tin dog. Their later adventures involved the Fendal, Pluto (and their tax collectors), and the Oracle. When he returned to Gallifrey, the Doctor became power-mad and insane when he gained the Lord Presidency from Borusa while dealing with the Vardans and the Sontarans; the behavior change was later revealed to be part his plan. During the course of the plan, he banished Leela from the Citadel where she'd formed a resistance force and met the Gallifreyan guard Andred. After this event, Leela stayed behind on Gallifrey with K9 remaining with her. Despite his sadness over losing his two companions, the Doctor pulled out a crate while in the TARDIS containing the K9 Mk II.
Before he put the new tin dog together, the Doctor continues his travels; he briefly traveled with a young man named Oliver Day. After seeing Oliver off, the Doctor took up residence in Sussex 2009 in a cottage dubbed Nest Cottage. During this period battling the Hornet Queen, he met Fenella Wibbsey in 1932 Cromer; under his protection, Mrs. Wibbsey became his housekeeper and set up psychic blocks to prevent the Hornets from taking control again. The Doctor
Several short trips (and a fully built K9 and another made for Sarah Jane as a gift) later, the Doctor was summoned by the White Guardian who gave him the task to find the all six segments of Key to Time in order to assemble it bring the entire universe to balance. The Doctor and K9 wouldn't be alone, however. The White Guardian gave him a new companion; the Time Lady, Romanadvoratrelundar (or Romana for short). Their early grievences towards each other aside, the two Time Lords made their way to find the first five segments located on Ribos, Zanak, Boscombe Moor, Tara, and Delta III. However there were a few dead ends during the course of the quest: one of which was in Shanghi, the Tomb of Valdemar and a avatar universe contained the Doctor's incarnation and his companions. The TARDIS crew landed on the war-torn Atrios in search for the final segment. Upon dealing with the Shadow (the Black Guardian's agent) and bumping into another Time Lord called Drax, the Doctor and Romana discoverd the sixth segement was in the form of Princess Astra. The situation proved difficult once all they segement was in place as the Black Guardian (under the guise of his white counterpart) appeared in the scanner to get the Key to Time. Unfortunately for the Black Guardian, the Doctor disperse all six segments back to their respective locations. Preventing the Black Guardian from going after them, the Doctor installed the Randomizer onto the TARDIS console, so neither him nor Romana would no where they're going. Immediately after the quest, the Doctor and Romana were in Hampshire, 1929 when they found themselves investigating (albeit seperately) the disapperances of young women caused by a young man's prickly aunt who was releavled to be part of a race of aliens who were killed off by a spaceborn virus. Their later travels saw the Doctor, Romana, and K9 encountering the Conglomerate and they devilish CEO Cuthbert; once regarding the Laan, the other with the Daleks. They also traveled to the end of the 19th Century where the Doctor would reunite with Jago and Litefoot while investigating the mysterious Pugilist. Several adventures later, Romana regenerated; her second incarnation was the resemblance of Princess Astra.
Romana was picked up and their adventures resumed leading to their trip to Brighton. Of course, they arrived at the wrong season and the water damaged K9's circuits. As an alternative destination, the Doctor and Romana went to The Leisure Hive on Argolis. While there, the Doctor thwarted Pangol's (a genetically created Argolin) plan to clone an army in his image with the rejuvenation machine; during this event, the machine aged the Doctor up hundreds of years before it was reversed. Upon repairing the machine, the Doctor sacrificed the Randomizer; having enough of running away. While reparing K9, the TARDIS landed on Tigella where he was accused of stealing their Dodecahedron only to find the real culprit in the sole surviving Zolfa-Thuran known as Meglos. The creature was destroyed once the Doctor redirected the Dodecahedron's laser at him. Near the end of this adventure, the Doctor recieved a message from the High Council requesting that Romana to be brought back to Gallifrey much to her bemusement. The matter put a strain on the two Time Lords: Romana refusing to go back and the Doctor choosing to obey the order. Before the TARDIS could ever get to Gallifrey, they were sucked into a CVE (Charged Vaccum Emboitment) drifting into the pocket universe of E-
Space. Despite the coordinates being set for Gallifrey, the TARDIS landed on the planet Alzarius where some of the imhabitants were repairing their ship. During the couse of this, the Doctor and Romana encountered Marshmen and a group of young teens called the Outlers; among them, their leader Varsh and his younger brother Adric. After teaching the inhabitants how to fly their starliner and making an antidote for the Marshmen, the Doctor and Romana left Alzarius. Unknown to them, however, the young Alzarian Adric snuck on board upon curiousity; thus a stowaway. The Doctor and Romana next arrived on
an unknown planet where they came across the Vampire King and the Three Who Rule. It was this adventure that let to the two finding out about Adric with the Doctor vowing to take the young back to his homeworld (until he assumed Gallifrey was a better idea for the boy). After they left Ballustra, the Doctor found the gateway between their universe and E-Space. While at the gateway, the Doctor, Romana, and Adric came across a Tharil who wanted his people free from the deranged Rorvik (who also wanted out of E-Space). After Rorvik and his crew were killed, the Tharils were saved and much to the Doctor's surprise, Romana decided to remain in E-Space. The Doctor didn't object and decided to give her K9 as her parting gift. And with that, the Doctor, with Adric by his side returned to N-Space.
Upon their arrival back in N-Space, the Doctor and Adric were greated by the Keeper of Traken who called for his help in protecting the Traken Union fron a greater evil. With the help of the Consul Tremas and his only
daughter Nyssa, the Doctor and Adric stopped the Master (with his TARDIS disguised as Melkur) from ceasing control of the Source. Immediately after the TARDIS left Traken, the Master, surviving the exploded ship, took hold of Tremas; merging with his body, destroying his soul in the process. The Doctor and Adric had several adventures before he decided to take the TARDIS to Logopolis for a formula required in reparing the TARDIS' Chameleon Circuit. While there, he met an air stewardess named Tegan Jovanka who mistook the ship for an actual police box when her aunt's car broke down. Also on the planet was Tremas' daughter Nyssa, who was brought there by the mysterious Watcher. During the course of this event, the TARDIS (with the Doctor inside) shrank due to the Master's interference before it and him was restored to regular size. But it proved to late as the Master closed off the CVEs stopping the Logopolians from they duties and created a widespread of entropy in the process. As Logopolis vanished, the Doctor raced to the Pharos telescope to reopen all of the CVEs while Adric and Nyssa were taken out of the universe; only to find the entropy claimed her homeworld and her people). The Doctor succeeded in reopening the CVEs but not before he end up confronting the Master one more time. In the process, he hanged on to the the satelite dish before finally letting go and falling to his death. Horrified, Adric, Nyssa, and Tegan gathered around him just in time for him and the Watcher to merge; triggering a regeneration. Before their very eyes, the curly, toothy Doctor regenerated into a young, blonde man....