Might as well join the bandwagon; out of all the people that were on WORA, I think there were only four or five I'd actually RPed with on the MU*s I'd been on when it was up. A lot of these are from way back in the day when MU was my only real social outlet, and my playing has dropped off considerably since like, 2007. This list is starting in 1997 with Beast Wars MUSH and on to the most recent two, Multiverse Crisis and RenoMUSH, my last two apped places.
Active/Currently Being Apped PCs
Fallcoast: Bradley (Human Psychic)
Staff Bits for Active Games
Transformers: Genesis - Optimus Prime (codestaff)
Heroes and Villains MUX - Astronema (character staff)
Beast Wars: Transmetals - Aftershock (headstaff/founder)
Beast Wars: Shadow World - Elmer (code assistant)
Megaman MUSH - Venus (Civilian staff), then Luna (codestaff)
Megaman X MUSH - Sword Man (headstaff/founder)
Transformers: Robots in Disguise - Elmer (character staff)
Digimon MUSH - Tank (Codestaff)
Millenium Heroes MUX/SuperMUX - TPstaff (don't remember which bit, probably Garrett)
There are probably more that I am forgetting as well
Player Characters, in no particular order
Multiverse Crisis - Tsukino Usagi/Eternal Sailormoon (Sailormoon theme), Return X (Megaman X theme), Garrett (Saint Seiya Omega theme), Klein (Sword Art Online theme), Annie Oakley (Pokemon theme)
Transformers: Genesis - Optimus Prime, Velocity
Transformers: The Rebirth - Gavin/Vindicator, Velocity, Optimus Prime
Beast Wars: Transformers - Aftershock, Nightwind, Impact, Artemis
Beast Wars: Transmetals - Aftershock, Impact, Imp, Majesty (character transfer), Megatron, Riptide
Beast Wars: Shadow World - Majesty
Heroes and Villains - Astronema, Tomoe Hotaru/Sailorsaturn, Andros/Red Astro Ranger, Brooklyn (Gargoyles), Eudial, Kou Seiya/Sailorstarfighter, Harley Quinn
Megaman MUSH - Rock, Roll, Alia, Rainbow Stallion, Supragenius Labmouse, probably many others I can't remember
Megaman X MUSH - X, iX, Signas, Alia, Dr. Doppler, Necromancer Arachne, Aftershock Ankylosaur
He-Man MUSH: Mix (OC Horde Soldier, Chiemical Warfare Specialist), Adora/She-Ra
Transformers Victory 2nd - Karone
Millenium Heroes MUX/SuperMUX - 2035/Beyond Bruce Wayne, 2035/Beyond Garrett Miller/Clayface, Killer Croc, Psylocke
MetaMUX - Aya Brea
Beast Wars Complete - Optimus Primal
Beast Machines - Drillhorn
Transformers Robots in Disguise - Bumblebee
Masterforce MUSH - Hot Rod/Firebolt
Pokemon: Evolutions - Giovanni, Annie Oakley
X-Men: Evolutions - Gavin/Portal
X-Men Evo: Bayville - Gavin/Gate
Zelda MUSH - Bongo-Bongo, Aidan
Videoland MUSH - Master Hand (TPstaff/Brawl Tournament Organizer), Chai Xianghua (Soul Calibur cast)
Bishoujo Sensi SailorMUX - Kino Makoto/Salorjupiter, Chiba Mamoru/Tuxedo Mask
Phoenix MUCK - Ayeka (Tenchi Muyo theme), Screw Masaider (Rockman X theme), Kinomoto Sakura (CCS theme), X (Rockman X theme)
Transformers 2005 - Wildrider, Trailbreaker, Wheelie, Geo
PernWorld MUCK - Galen
Digimon MUSH - Gavin/Cubmon
MatrixMUSH - Medea
RenoMUSH - Paul (Lancea et Sanctum Nosferatu)
There's tons of others that I'm forgetting specific MU* names for, and just have general recollections, like the superhero MU* I played an OC who could absorb inorganic matter and take on its properties.