Jason Wynn - Former CIA director and Al Simmons' superior that gave the order to kill him. Ruthless, cold and at one point, one of the most powerful men on the planet. Currently he has lost most of his influence with Spawn having eliminated most if not all his means of regaining power.
Cogliostro/Cain - Spawn's former mentor and guide; current master of the eighth circle of Hell
Wanda Blake - Al Simmons's widow; after his death, she married Simmon's best friend, Terry Fitzgerald, and had a daughter with him, Cyan. She kept her maiden name both times when getting married, much to her grandmother's dismay. She later has twins with Terry, which turns out badly, as they are both reincarnations of God and Satan. The character is named after the wife of Spawn creator, Todd McFarlane.
Christopher - A boy whose soul was sealed within Spawn's heart. He has taken the form of a young Hellspawn and uses his powers to help Spawn. He is the key to The Legion, the one who actually releases them from Spawn.
Thamuz - A demonic Master of Torture who has vowed to unravel the secrets kept by Spawn.
Kali - A dark goddess who battles against Spawn. Another incarnation of the Mother
The Mother - The Mother is the creator of the universe and all the worlds within it. She is neither male nor female but is referred to as Mother by Jake and Katie (God and Satan). It was she that removed God and Satan from their thrones while she attempted to unify mankind, and also her that impregnated Wanda with their human forms.
Nyx - A witch who helped Al Simmons regain his Hellspawn powers, only to betray him so that she could journey to Hell to save the soul of a friend. She appears to be attuned to Greenworld. As of Spawn issue 169, Voodoo Child, Nyx reconciled with Spawn and regained her powers. She was instrumental in saving Spawn in Spawn issue 171, "A Tale of Three Brothers:Remembrance", from demons called Sin Eaters. In an interview conducted by CBR, Spawn writer, David Hine reveals that Nyx's powers may be developing and that she is in love with Spawn 
Marc Simmons - The brother of Al Simmons/Spawn. He is an FBI profiler and field agent.
Richard Simmons - The brother of Al Simmons/Spawn. He is a minister first revealed in issue 170, "A Tale of Three Brothers: Hellhouse". He ran a building where he and a companion would show visitors films/depictions of people's most despicable acts in the attempt to sway them from wrongdoing. That is until the demons Ab and Zab appear who opens portals to hell in his facility. He and his companion are attacked and fed on by sin eaters until they are saved by Spawn and Nyx. Richard Simmons was a drug user in the past due to the influence of Mammon under the guise of Malefick. It is later revealed that Richard Simmons harbors much guilt for what had become of his brother, Al Simmons since he was involved in the set of events that led to Al Simmons committing his first murder when he stabbed the drug dealer Weasel. Though Spawn/Al Simmons had not shown any anger but instead compassion for him, Richard is unable to forgive himself from his past wrongs, and with the help of Mammon allows himself to be swallowed up into hell.
Antonio Twistelli - "Tony Twist" the infamous mafia don of New York City. He's been making a play for the top and seeks to inherit the power of Don Bartino. Cruel, ruthless and smarter than he looks. Oversaw both mafia supersoldier projects. With Spawn and Violator causing so many problems in New York, his plans for advancement look in jeopardy.
OvertKill - Seemingly unstoppable cyborg who fought Spawn to a stand still early in his career. Was defeated by a simple systems malfunction. Each time he's dismantled he comes back stronger and more dangerous than before.
Tremor - The predecessor of OvertKill. He is a failed prototype for the Mafia Supersoldier. The process turned him into a cybernetic monster resembling a large demon, and for this he continues to wage his own personal war on the mob. Depending on his mood Spawn can't be sure if he will be a friend or a foe when Tremor comes calling.
The Curse - Phillip Krahn. Eccentric billionaire, religious zealot and one of Spawn's deadliest enemies.
Cy-Gor - A cybernetic mesh of metal and ape but with a human brain. This government project knows no control nor pleasure except for the taste of blood.
Urizen - The Dark God, Leveler of Hope and Destroyer of Dreams.
Bobby - Bobby is a homeless which was Al's best friend in the first 70 issues. Once, Bobby got shot in the head and Spawn revived him, using a lot of his powers. Bobby was the only homeless along with Bootsy to have appeared in several issues, have a storyline and a name. Little is known about him except that he once had a wife and a daughter but when his wife passed out he became an alcoholic and slowly lost everything he had, including his daughter. Bootsy being his best friend, he was really saddened by his death and fell deeper into alcoholism going as far as stealing a dead hobo's bottle which made him suspected of murder. There's been no news of him since Spawn made everyone including Cog leave his alleys.
Bootsy - First introduced as a homeless, Bootsy was in fact, an under-cover angel that watched over the Spawn and made reports to heaven about him. After a fight with The Heap, Spawn was killed. Bootsy revived him in order to prevent the armageddon. When he revived him, he got abducted by other angels for having interfered with humans' fate.
Ab and Zab - Their real names are Abbadon and Zabraxas. They are minor opener-demons who serve the Lord of Hell. They've been both Spawn's enemy as well as minions and there's just some things about being on Earth they can't get enough of... cigarettes, guns, booze, babes and any other vice you can think of. As of Spawn issue 170, "A Tale of Three Brothers: HellHouse", they are responsible for opening a rift to hell, allowing the Sin Eater demons to attack humans.
The Redeemer - A holy opposite to the Hellspawn, created by the Star Chamber.
Tiffany - A warrior-angel who replaced Angela in the hunt for Spawn. A member of an angelic host known as the Amazon Warriors.
Callindra - A young 200 year old angel. Her first case was defending Angela on charges of treason.
Anahita and Kuan Yin - Two angels attempting to help clear Angela by bringing Spawn to testify on her behalf. Both went freelance with Angela.
Rafael - Current highest-ranking angel on Earth, taking over as Gabrielle is called to answer for her failed scheme.
Unlike popular belief, when characters die in "Spawn" they usually don't come back. If they do, they come back as ghosts.
Billy Kincaid - A child-killer who was in turn killed by Spawn. He went on to serve as a lackey of Malebolgia and has returned from Hell multiple times to wreak havoc. He was stopped once by Spawn and most recently by young Christopher.
Margaret Love - A “philanthropist” who Simmons once knew as Soviet agent Nadia Vladova, specializing in mind control experiments with a high death/insanity rate. Spawn discovers her homeless shelter program is a cover for harvesting human heads for remote controlled cyborgs as part of the arsenal for her ultimate solution to human greed, a worldwide nuclear assault. She dies after Spawn allows falling debris to kill her but launches one missile toward New York as she dies.
Angela - An angelic bounty-hunter sent against Spawn who later befriended him. She was impaled with her own dual bladed staff by Malebolgia, which would lead to Spawn's taking her sword and cutting off Malebogia's head shortly afterwards.
Malebolgia - Former master of the eighth circle of Hell. Decapitated by Spawn. Exists now as a something of a ghost possessing the Freak's necroplasmic body, gathering other parts of his divided being from people on Earth to fully become himself again.
The Freak - An escapee from a mental asylum with multiple personalities. He's a sadistic murderer who believes his own delusions. Freak's tangled with Spawn and The Violator, and stole the bag of necroplasm that turned Eddie Beckett into The Heap. Spawn killed him with his own evil and he resided in Hell. A necroplasmic body was resurrected and is possessed by Malebolgia but may contain the Freak's soul as well.
Simon Pure - The last leader of The Kingdom, a vampire cult that believed (incorrectly) that they were descended from the 12 apostles of Jesus, God's chosen race and awaited a cleansing in which the wicked would be wiped from the Earth and the vampires would rise to power. He and his followers were viewed with distaste by all other vampires. Simon Pure was a particularly religious zealot who took it upon himself to initiate the prophesized "cleansing", creating an army of 777 vampire warriors blinded by Pure and then gifted with a "second sight" to see sinners as marked. Simon sent the army into New York to slaughter all the sinners, but his plan was foiled when Spawn absorbed all of New York's sins into himself and lured The Kingdom to send themselves into a doorway made by the demons Ab and Zab.
Jade - First introduced in the animated series as Lisa Wu, a news reporter who is investigating the alley murders at Rat City and who later helps Sam and Twitch find more information about the people responsible for the murderers as well as help Wanda Blake understand her situation with the Hellspawn. She is actually a bounty hunter who was sent to kill the Hellspawn, but later befriends him as she understands that he is different from the others she has killed. In the series it is revealed that she has been sent by the heavens for centuries to kill the evil followers so much so that she even was sent to kill Genghis Khan. She is later killed by Spawn in order to be sent to the Elysian Fields to escape two assassin warriors who were sent to kill her for treachery for not killing him. Before her body is taken away by the assassins, Spawn asks if she would be at peace, one of them answers "Yes, something that you will never know, Hellspawn."
Lilly - First introduced in the animated series as a teenage girl arriving at a bus stop and involved in two more alley murders near Rat City investigated by Sam and Twitch. She is actually a vampire offered a deal by the heavens to kill the Hellspawn. She is later killed by Spawn with sunlight.
Medieval Hellspawn - As the name suggests, this was a hellspawn of a medieval era. He was a knight named Sir John of York, who fought during a civil war in England. He was released from service to Henry II after he and three others mistakenly killed the Archbishop of Canterbury (they mistook some angry words by the King as an order). He was killed on a battlefield in Ireland by the King's bodyguards as he approached King Henry for forgiveness. For his past deeds of killing (and enjoying it), John was sent to Hell, where he, like others made a deal with Malebolgia. He was returned to Earth, several years in the future and clad in medieval looking symbiotic armor. Upon realizing what had happened (which was helped along with him finding his own grave), John traveled throughout England, doing good deeds in the hope he would be redeemed. He was eventually slain by the demon hunter Angela.
Alicia - The next top Hellspawn Slayer
Anahita - Close friend of Angela.
Csheriece - Hellspawn slayer of Angelic Darkness
Domina - A leader of a sisterhood of angels which includes Lilith.
Gabrielle - Head of Heaven's headquarters on Earth.
Immaculata - the assassin angel, killed by Cogliostro
Jackie - Retired Hellspawn slayer
Javon - Male Hellspawn slayer
Kuan Yin - Close friend of Angela.
Lilith - An angel who volunteered to kill Spawn after Malebolgia's defeat.
Lotus - A mystical samurai angel sent during the samurai wars
Mai - A Witch Hellspawn slayer
Miranda - Hellspawn slayer and leader of the angel warriors
Nuria - A Hellspawn slayer from Egypt
The Redeemer - The Anti-Spawn, wielders of Angelic Fire
Scarlet - Amazon Hellspawn slayer
Tiffany - Rookie Hellspawn slayer (battles Spawn in issues #44 and #45)