Here’s two day’s worth of posts according to the schedule, because “what is your favorite character you never played” seems like a clown question to me, if it is asking about characters you made up and then never used. I don’t really invest enough in a character during generation to care about them. They only grow on me after I play them for a while.
So my favorite D&D character is pretty easy — the only one that played for an extended period was a half-orc fighter/thief named Swidthef. (The first or second Dragon magazine I ever owned had a table of Anglo-Saxon name elements which is where the name comes from. ) Swidthef started off in a party which included an elf magic-user/thief and I don’t remember what the third character was. He would mostly adventure solo though, and somehow rose up to 8th/8th or something like that, having survived a few TSR modules (including one of the Desert of Desolation modules and maybe the Lost Caverns of Tsojcanth?) as well as innumerable adventures my brother dreamed up. I don’t have a ton of vivid memories apart from from a few vignettes: using a garrote to kill some kind of giant insect (while it was flying & Swidthef was on its back); assassinating a paladin by pushing him into a pool of quicksand & then saving him, resulting in an alignment shift; planning to travel to Kara-Tur to exterminate ninjas shortly after Oriental Adventures was published. In the beginning of his career I think he also came p with some stupid inventions: broken coconut shells filled with pepper for use as grenades, blades concealed in his garments to cut through bonds should he ever be captured, and so on. Maybe those were the work of the magic-user/thief though.
Sadly I did not keep the original character sheet, but I did find a revised version of the character which toned down the suspiciously high rolls he had for his stats and retconned him into a single classed assassin of 9th level … somehow his magical bastard sword, looted from a module, had been ground down to a short sword, no doubt to be more concealable.
I’ve had characters I’ve enjoyed playing more in other games, but for D&D, Swidthef is still the high water mark.
If the ‘favorite character not played’ means my favorite character that someone else played, that’s pretty hard to answer too. I’ve really liked most of the characters in my current and previous D&D campaigns, each for their own reasons: Grundle the misunderstood dwarf, who is constantly trying to maximize the party’s effectiveness by redistributing magic items — and accused of hoarding all the magic by his allies; Silbahn, the reluctant paladin who is always a hair’s breadth from losing his paladinhood, but occasionally redeems himself by risking death for his allies and mentoring a gremlin who idolizes him; Mazrim, the often-maligned assassin who was raised from the dead, over and over, after each misadventure, but grimly kept trying; Turbendish, a magic-user who wrote confounded letters home describing the ridiculous town the party is headquartered in and their barely-coherent antics; Dell, an insomniac, world-weary rogue who finally retired from adventuring; Jerome, a bard who is slightly less clever than he thinks but somehow manages to salvage his situation whenever his tapestry of lies is pulled apart; Willis, the suicidal cleric who walked the line, bordering heresy, with Silbahn; and so on.