If you've got eight hours to spare and a strange desire to watch a guy run through the entirety of Diablo 2 without taking a swing at anything, then this is your very specifically lucky day: A fellow by the name of DrCliche managed to do just that, and has shared the whole thing on YouTube.
The good doctor explained how he got through it on Reddit, and there's more to the run than just hauling ass all over the countryside. He began with "chest farming" the house nearest the Rogue encampment in the opening act—hence the repeated saves and restarts—and shopping for specific equipment from Charsi, and then slowly (and very carefully) leveling up along a particular, survival-geared path.
As is often the case with speedruns, the rules for Diablo 2 Pacificist runs are a little arbitrary, and they don't include not killing anything: In fact, one of the first orders of business was to find and equip "Thorns" armor, which deals counter-damage when the character is hit, and later the Shiver armor, which inflicts cold damage on enemies who land a blow.
This is necessary, because pacifist or not, boss enemies do have to die in order to advance the game, and as you can see around the 2:22 mark in the fight against Andariel, the only way to make it happen is to stand there and take the abuse, and let the passives do their thing. It's a tedious but relatively straightforward process, except for the Act Four "Chaos Sanctuary" boss Lord de Seis, who doesn't have a melee attack, and whose ranged and elemental attacks don't trigger Nova Shield—the only damage source in the game that doesn't do so. On top of all that, Lord de Seis can heal himself with the Bestow spell.
"But De Seis's elemental attacks do proc Chilling Armor, and at level 30, with Cold Mastery, 6 points in Chilling Armor, and a +2 staff, you do damage quickly and consistently enough to keep Lord de Seis from ever casting Bestow," DrCliche wrote. "Diablo is almost a joke in comparison, but do watch out for his Lightning Snake."
The real trouble, though, is found in the Hellforge in Act Four. "The Hellforge has a 1 in 11 chance of dropping an Amn rune, completing your Edge," he explained. ["Edge" is a three-part Runeword that works in three-socket bows, granting a level 15 Thorns aura when equipped.] "Without the level 15 Thorns provided by Edge, it would be wholly impractical (if not impossible) to continue. If you don't get the Amn, the first monsters that can drop one are the Council Members in Act 3, but Amn drops in Normal are exceedingly rare. If the Hellforge doesn't deliver, your run is over."
But after that, it's smooth sailing. "Act 5 is simple and easy," DrCliche wrote. "Teleport to the Ancients, and then Baal, and bravely weather the storm until they submit to your moral superiority."
Nice work, DrCliche, even though I suspect PETA probably still won't support this particular brand of pacifism. They're probably penning a "Won't someone think of the demons?" press release as we speak.