NOTE: The following contains words, titles, names, and terminology from a buncha different editions that may mean different things to different people. Please do not get your panties into a bunch because I use am using a word or title differently than you think/want or applying terms you disagree with. I'm just spit-ballin' here...total hypothetical for 5e. Doin' my best to give the OP what he's asking for. /NOTE
[EDIT] Forgot the "examples" for most of them. heh heh. oops.[/EDIT]
Avenger: The avenger is a master of stealth using hard fast hitting, often capable of incapacitating (if not killing) in a single blow, in the service of some personal cause. Disguse/spying, Stealth skills/abilities, Bonuses to use of "small/simple" weapons (daggers, hand crossbows, bolo, etc.) Apply Alignment restriction to "non-Lawful" if/as desired.
Examples: Batman, Assassin's Creed.
--Assassin: is an Avenger with the Assassin Theme who has no qualms about killing, be it for profit, a personal vendetta or some greater cause. "Kill Attack", Poison Creation/Use and attack/to hit and damage bonuses other classes do not possess as part of their "package/theme." Apply Alignment restriction to "Evil" or "non-good" if/as desired by the DM.
--Ninja: is an Avenger with the "Shadow weaver" Theme. They receive skills/abilities similar to the Assassin plus special shadow magic ability. Apply Alignment restriction to "Evil" or "non-good" if/as desired by the DM.
Champion: The champion is a skilled warrior who fights for a cause. Similar to the avenger, this cause might be personal gain, profit, religious in nature, or some "greater ideal/code" they stand for. Heavy armor and weapon proficiencies, invoking "auras" of various effect as relates to their cause.
Examples: Galahad, Lancelot, Joan d'Arc, Sir Roland, the Jedi, pretty much any "knightly" sort you can think of.
--Paladin: is a champion who possesses the "Order/Law/Good/Divine/Holy/etc." Theme, fighting for the "greater good" of their church/deity. Heavy hitting against Evil creatures, demons and undead and various divinely granted gifts/powers. Apply Alignment restriction to "LG" or "G" if/as desired by the DM.
--Cavalier/Knight: is a champion who possesses the "Order/Law/Noble?/Valor?/etc." Theme, fighting for their cause of choice but doing so mostly from combat. Heavy hitting from horseback, additional damage against chosen "sworn enemies" (of the crown, country, deity, people, etc. whatever is against the Knight/Cavalier's chosen code/cause/ideals) and receiving various gifts/powers of diplomacy and nobility. Apply Alignment restriction to "any Lawful" if/as desired by the DM (the cavalier/knight has rules/codes/ideals they believe in and follow, just not as stringently or divinely oriented as a Paladin) .
Fighter: The fighter is the master of combat, arms and armor, whether specialized or a "man-at-arms" with any weapon, the fighter strikes most often, does more damage, and is tougher overall in a "fight" than other classes.
Examples: Beowulf, Conan, Fafrd, Madmartigan, Man-at-Arms from MotU.
--Barbarian: is a fighter who possesses the "Berserker/Savage/Rager/Primal/etc." Theme. They are able to hit harder and do more damage in a single blow through their sheer physical strength and determination than other classes. Skills/Abilities include tracking, resistance to magics (containing the savage mind of a Barbarian in a rage is nearly impossible), resistance to poisons (overcoming the Barbarian's immense fortitude/constitution is equally difficult) and heightened senses, in addition to added/bonus damage. Apply Alignment restriction to "any Chaotic" if/as desired by the DM.
--Warlord: is a fighter who possesses the "Strategist/Noble?/Veteran?/Leader/etc." Theme. They exude command on the battlefield moreso than any other class and are able to bolster and organize their comrades to heights they might not achieve alone. Skills/Abilities include imbuing temporary hit points, combating the effects of awe/fear/confusion, in addition to added bonuses in hitting/attack.
Cleric: The cleric is the defender, teacher, preacher and fighter of their faith/church/deity. They receive divine spellcasting, use of armor and limited weaponry (as allowed by their order), and divinely granted/gifted powers (turning undead, specialty priest/god-domain powers, etc.)
Examples: Archbishop of Canterbury, Turpin, Friar Tuck, Aleena (from BECM).
--Shaman: is a cleric who possesses the "Totemist/Savage/Primal/Rager/etc." Theme. They are the "holy men", speakers and dealers with "the unknown" of their tribe/culture, capable of healing and bolstering as well as speaking with and evoking spells/favors from their sacred totems, spirits and the "spirit world."
--Priest: is a cleric who possesses the "Ritualist/Divine/Diplomat?/Leader?/Oracle/Cloistered?/etc." Theme. They forgo the use of armor and most weaponry of the true cleric in exchange for a more intimate relationship with their divine power, imbuing them with greater spell-casting potential and influence over the faithful.
Rogue: The rogue may be a master of various abilities of stealth and thievery or a jack-of-many trades/skills relying on speed and skill to make their attacks. Skills/abilities include Stealth, Thievery, Sneak Attack and finding/removing (and laying) traps.
Examples: The Grey Mouser, Gord, Will Scarlet.
--Thief: is a Rogue who possesses the "Sneak/Snitch/Footpad/Streetwise/Locksmith/etc." Theme specializing their skill sets with getting into hard-to-reach places and taking what is there, increased skill with Thievery and Stealth. Apply Alignment restriction to any "non-lawful" if/as desired by the DM.
--Bard: is a Rogue who possesses the "Minstrel/Performer/Orator/Nature/Loremaster/etc." Theme. While receiving many of the Skills/Abilities of the Rogue, they also are able to use magical music to varying effect, including healing and bolstering their companions, certain natural and illusory enchantments, and highly charismatic and diplomatic in social settings able to glean/gather/overhear tidbits of information on a wide variety of subjects.
Mage: The mage is the masters of magic, some call him a wizard, some call her a sorceress, but all hold them in awe, fear or cautious respect for their command of the occult and the arcane. Arcane Spell use is the skill/ability of choice before any armor or the simplest of weapons and their ever-increasing knowledge on a variety of subjects few other classes would ever even hear or be aware of is unparalleled.
Examples: Merlin, Morgan Le Fey/Morgaine, the Lady of Shallot, Evil-Lyn from MotU.
--Spellweaver (nee Sorcerer): is a mage with the "Magic Lineage/Innate Adept/Enchanter/Mystic/Arcane Destiny/etc." Theme. Their ability to summon energies and form spell effects through their sheer force of will and/or hereditary bloodline, more often though generally less powerful than a true "Mage", is sometimes envied by those who are more reliant on their studies and mystic tomes, though the spellweaver is likely to have these as well.
--Witch: is a mage who possesses the "Herbalist/Medium/Nature/Moon-worshipper/etc." Theme. Their skill with the making of potions, potent "hexes", and ability to channel/speak with spirits and the dead is often misunderstood and viewed with caution and fear moreso than reverence. They may not have the capacity for the intense study to master the diversity of the mage's grimoire, but their alternate abilities can make the experienced witch just as powerful a dealer in the arcane as any mage.
Warlocks, Monks, et al. to come later.
--SD