A handy little guide for anyone interested in getting into Classic Who but are unsure what order the stories go in or which ones contain missing episodes.
First Doctor
An Unearlthy Child
The Daleks
The Edge of Destruction
Marco Polo (all missing)
The Keys of Marinus
The Aztecs
The Sensorites
The Reign of Terror (episodes 4–5 missing but restored with animation for the DVD release)
Planet of Giants
The Dalek Invasion of Earth
The Rescue
The Romans
The Web Planet
The Crusade (episodes 2 & 4 missing)
The Space Museum
The Chase
The Time Meddler
Galaxy 4 (episodes 1, 2, & 4 missing)
Mission to the Unknown (missing)
The Myth Makers (all missing)
The Dalek’s Master Plan (episodes 1, 3–4, 6–9, & 11–12 missing)
The Massacre of St Bartholomew’s Eve (all missing)
The Ark
The Celestial Toymaker (episodes 1–3 missing)
The Gunfighters
The Saveages (all missing)
The War Machines
The Smugglers (all missing)
The Tenth Planet (episode 4 missing)
Second Doctor
The Power of the Daleks (all missing)
The Highlanders (all missing)
The Underwater Menace (episodes 1 & 4 missing)
The Moonbase (episodes 1 & 3 missing)
The Macra Terror (all missing)
The Faceless Ones (episodes 2 & 4–6 missing)
The Evil of the Daleks (episodes 1 & 3–7 missing)
The Tomb of the Cybermen
The Abominable Snowmen (episodes 1 & 3–6 missing)
The Ice Warriors (episodes 2 & 3 missing)
The Enemy of the World (episodes 1–2 & 4–6 missing)
The Web of Fear (episodes 2–6 missing)
Fury from the Deep (all missing)
The Wheel in Space (episodes 1–2 & 4–5 missing)
The Dominators
The Mind Robber
The Invasion (episodes 1 & 4 missing but restored with animation for the DVD release)
The Krotons
The Seeds of Death
The Space Pirates (episodes 1 & 3–6 missing)
The War Games
Third Doctor
Spearhead from Space
The Silurians
The Ambassadors of Death
Inferno
Terror of the Autons
The Mind of Evil
The Claws of Axos
Colony in Space
The Dæmons
Day of the Daleks
The Curse of Peladon
The Sea Devils
The Mutants
The Time Monster
The Three Doctors
Carnival of Monsters
Frontier in Space
Planet of the Daleks
The Green Death
The Time Warrior
Invasion of the Dinosaurs
Death to the Daleks
The Monster of Peladon
Planet of the Spiders
Fourth Doctor
Robot
The Ark in Space
The Sontaran Experiment
Genesis of the Daleks
Revenge of the Cybermen
Terror of the Zygons
Planet of Evil
Pyramids of Mars
The Android Invasion
The Brain of Morbius
The Seeds of Doom
The Masque of Mandragora
The Hand of Fear
The Deadly Assassin
The Face of Evil
The Robots of Death
The Talons of Weng-Chiang
Horror of Fang Rock
The Invisible Enemy
Image of the Fendahl
The Sun Makers
Underworld
The Invasion of Time
The Key to Time Part One: The Ribos Operation
The Key to Time Part Two: The Pirate Planet
The Key to Time Part Three: The Stones of Blood
The Key to Time Part Four: The Androids of Tara
The Key to Time Part Five: The Power of Kroll
The Key to Time Part Six: The Armageddon Factor
Destiny of the Daleks
City of Death
The Creature from the Pit
Nightmare of Eden
The Horns of the Nimon
Shada
The Leisure Hive
Meglos
Full Circle
State of Decay
Warrior’s Gate
The Keeper of Traken
Logopolis
Fifth Doctor
Castrovalva
Four to Doomsday
Kinda
The Visitation
Black Orchid
Earthshock
Time-Flight
Arc of Infinity
Snakedance
Mawdryn Undead
Terminus
Enlightment
The King’s Demons
The Five Doctors
Warriors of the Deep
The Awakening
Frontios
Resurrection of the Daleks
Planet of Fire
The Caves of Androzani
Sixth Doctor
The Twin Dilemma
Attack of the Cybermen
Vengeance on Varos
The Mark of the Rani
The Two Doctors
Timelash
Revelation of the Daleks
The Trial of a Time Lord Part One: The Mysterious Planet
The Trial of a Time Lord Part Two: Mindwarp
The Trial of a Time Lord Part Three: Terror of the Veroids
The Trial of a Time Lord Part Four: The Ultimate Foe
Seventh Doctor
Time and the Rani
Paradise Towers
Delta and the Bannerman
Dragonfire
Remembrance of the Daleks
The Happiness Patrol
Silver Nemesis
The Greatest Show in the Galaxy
Battlefield
Ghost Light
The Curse of Fenric
Survival
Eighth Doctor
TV Movie