I've played a few...
"Scout" was a 24th-Century Explorer who found "Modern Life" just too stinkin' violent, and rebelled. While he could shoot an alien beast who was trying to eat him, he preferred to do it with a tranquilizer dart... and then, he took Engineering... Rick, my GM, was the kind of guy who tried to work with you, and allow the players to have the adventure they wanted to have. My PC wanted to develop some new, non-lethal weapons, and I made up a series of tasks, and he approved them...
In the first episode, my PC had a tranquilizer rifle, and when we were attacked in a "McDugle's", ripped the table from its bolts in the floor, overturned it, and used it for cover, checked his dead buddy, then used the napkin-holder as a missile weapon. After the gunman left, he went and got his rifle.
In later episodes, he took a 24th-Century airgun, and developed an "Autoinjector Magnum" which fired Stun rounds, and used that against any non-hard targets. He also developed an Armored Hostile Environment Suit that protected him from anything short of plasma bursts, and gave him some special abilities... Of course, he was a survivor, and also carried a modified, optimized sniper rifle with a rifle-integral grenade launcher, and loaded that with Armor-Piercing, High Explosive grenades, for targets which WERE hard.
In 1e D&D, I played a pacifistic Ranger who wouldn't kill. The GM didn't work with me, and I never played with her, again, so I don't recall much. I remember him using a Spetum against an attacking Badger...
In another Sci-Fi game, I had another character who would kill, if forced to, but who used weapon tech to avoid it. She invented her own weapons, too. Tangler Grenades and Needler Pistols (along with a "Bolacaster", sort of a crossbow, to throw grenades) were her things.
I also invented "The Eternal Order of the Militant Pacifist". This bunch were in some version of a D&D world, and recognized that a pacifistic life was problematical, but persisted, nonetheless! Today, this would be a Divine Core Class, with restricted weapons (Knife - because all Commoners have'm, Club, Sling, & Staff - because anyone can find or make them, and a plethora of special weapons, such as the Sai, Ranseur, Spetum, Sap, Hookless Net, and other weapons that disarm, trip, or do non-lethal damage. Spells included all healing and "damage repair" spells (such as Restoration, for instance), as well as Charms, Holds, Sleep, Web, etc.
Non-lethal damage, disarming, tripping, etc., are all allowed, and encouraged, IN ORDER TO SAVE LIVES! However, causing any lethal damage results in -1 XP/HP. Naturally, that doesn't apply to non-living Constructs/Undead.
Other weapons are generally disallowed, unless there is a good excuse. Using a bow with Sleep-arrows, for instance. Lethal weaponry can result in expulsion from the order.
More importantly, Militant Pacifists are all about fighting! These are not your Amish, these are folks who will step up and oppose the agressors! At first level they get Improved Unarmed Strike (for the no-Attacks-of-Opportunity), and Merciful Blow (no -4 to use non-lethal damage with any weapon they're proficient with). Second level brings Improved Disarm & TWF (for use with the Staff). Third level was Improved Trip and... something.
In short order, they were able to move up, disarm their opponents, knock them down, and grapple or net them. They also had a small selection of spells and healing, as well. They were more limited than Clerics, in general, but fun (to me, at least). I thought a tough-but-gentle healer was a cool idea, but I don't recall who, if anyone, ever played one... And no, I don't have the class description handy. Sorry!
Skills should be a combination of Cleric's & Rogue's. Hit Dice & BAB as the Cleric, I guess. Any armor/shield (including tower). Skill points? Probably more than the Cleric, since weapons & spells are so limited... 6-8.
Anyway, you can make one of your own, if you want. Yes, it IS possible, in D&D. And it can be fun, too!