Superman: The City of Tomorrow

Artemis

DC, Olympian goddess

Wonder Girl

Donna Troy

Red Tornado

an android, Ulthoon / John Smith

Lobo

DC, bounty hunter

Jor-El

Kryptonian father of Kal-El (Superman)

Talia al Ghul

from Batman

Ra's al Ghul

from Batman

Steel

John Henry Irons

Impulse

Bart Allen

Lara

Kryptonian mother of Kal-El (Superman)

Vandal Savage

Vandar Adg, DC from Batman

Mercury

from The Metal Men

Maggie Sawyer

DC

Natasha Irons

Steel / Starlight / Vaporlock

Platinum

from The Metal Men

Lead

from The Metal Men

Gold

from The Metal Men

Metallo

John Corben

Pete Ross

from Superman

Iron

from The Metal Men

Lucy Lane

sister of Lois Lane

Tin

from The Metal Men

Will Magnus

creator of the Metal Men

Flashback

Sara Quinones, Milestone

Ocean Master

Orm Marius

Amazo

android, Justice League villain

Ron Troupe

of the Daily Planet, DC

Kelex

DC

Etrigan the Demon

Jason Blood

Clock King

William Tockman

S.T.R.I.P.E.

Pat Dugan

Thor the Thunder Dog

Manhunter's pet dog

Secret

Greta Hayes, New Earth

Lena Luthor

Lex Luthor's daughter

Arrowette

Cissie King-Jones

Alice White

wife of Perry White, from Superman

Sarah

wife of Abraham, generic, from the Abrahamic religions

Scavenger

from Superboy

Doctor Spectro

DC; Thomas Emery

Hourman

853rd century android, Matthew Tyler, 1999-present

Bonnie

Queen of the Seas, companion of Black Pirate

Brainiac

Modern Age DC, Vril Dox, 1999-present

Brainiac 13

64th Century incarnation

Mongul II

DC

Sledge

from Guy Gardner

Obsession

Dana Dearden

Viridium

Prince of Life, from Lords of the Ultra-Realm

Jerome Odetts

from Superman