It is unknown where exactly Igor came from or who he is, but he came to Castle Frank N. Stein at some point and was hired as an assistant. One of his duties was to dig up corpses from the nearby graveyard, something he objected to but was made to do. One rainy night, Igor's task was interrupted by a double-glazing salesman who came calling at the castle. Instead of going out to find a fresh corpse in the bad weather, Igor kept the salesman talking so he could kill him and provide a really fresh corpse for the professor. Igor oversaw the subsequent creation, although he was distracted by the loony Kevin the Bat, who he crushed a large mallet. Friends of the deceased mammal saw this and launched an attack on Igor, just as Chuck came to life. The assistant fought them high up on the platform used to resurrect Chuck, but the level came crashing down and seemingly decapitated Frank's new son. Thanks to Igor, the idea was put forward that Head could be Chuck's new head - and a two-headed monstrosity was thus born!
At first, it remained a secret that Igor had killed Chuck in order to get a fresh corpse, but the truth was outed when Detective Case came calling on a murder inquiry. Instead of being sent to jail, Igor "admitted" that it was Chuck who had killed the salesman. Case decided to chase Chuck around the castle with a gun, dragging Igor along for navigation (even though Igor would have happily volunteered). When Chuck was cornered, he used Head as a weapon on Igor to knock him out, forgetting that Case had the gun. Igor woke up in time to see Case knocked out by Chuck and discovered that Frank had gone on to replace Case's brain with Igor's grapefruit dinner.
Igor went on to become a constant thorn in Chuck's side, often berating him for his failures (even if he had been the cause of them). He took great satisfaction in correctly predicting that Chuck would make a fool of himself at the Monster of the Year award ceremony, but soon welcome the banished corpse back into the castle when Frank's Nanny arrived to cause havoc. Sneaking him in disguised as a tiny plant, the pair worked together to rescue a sick Head from Nanny's Mr Cuddle Bunny stories but all three were eventually thwarted. Spurred on by his hatred of those children's stories, Igor kidnapped the author and locked him away in the castle, intent on not letting write any more books. Unknown to him, Mr Cuddle Bunny had a typewriter in the room and written dozens more AND wanted to stay in the castle, all thanks to good friend Igor. Later, Igor invited his nephew Billy No-Friends to the castle to disrupt a painful fancy dress party and paid him to eat as much food as possible.
Thanks to Chuck being technically dead, Igor was dragged along to Hell with the others to determine who was actually dead. They were released when Frank was "captured" by the Thin Controller and soon tried to plan to get his employer back home (since he wasn't getting paid without him). His subsequent return saw Igor try and warn Chuck about the fragile support pillar, but he wasn't quick enough to prevent the entire castle falling down.
Later stories saw Igor's vindictiveness ramp up significantly. After returning from being nice (thanks to Peter the Perfect Pixie), he went on to oust Chuck to Colonel Boldwig-Smythe as the Two-Headed Monster, attempted to oust Chuck's addiction to Slurp-A-Cheese, convinced Chuck to sign up to Transylvania's toughest bank (before realising he had been signed up himself for medical experimentation), brought in a dog to terrorise the castle and tricked Chuck into going into the dungeons, well aware that vampires were waiting to eat him. On Chuck's birthday, Igor planted a bomb in the cake to get back at him further, but felt bad about doing it on such a day. When he attempted to stop Chuck from cutting into the cake (and bomb), Frank derided him as ruining his day again and kicked him out of the room, leaving Igor powerless to prevent the eventual blast. His final act was to turn up the heat on Frank's machine to "perfect" Chuck, almost roasting him to death. For some reason, Chuck winded up in a dream that he was Decap-Man and went on to save the world countless times. He was thwarted by the mysterious Mystery Man (man of mysterious mystery) who's "identity" turned out to be Igor.
- Igor is named after the classic "hunchback" character in many horror stories, derived from his appearance in the Decap Attack game.
- Igor is somewhat a supporter of Transylvania United, even owning a replica shirt, but he rarely fancies their chances against Black Forest Gateaux.
- Basher, a prefect who bullied Frank at school, bears a passing resemblance to Igor.
- The first page to feature Igor had him with red eyes. He has white eyes (like everyone else) ever since.
Igor appears in almost all Decap Attack stories, with few exceptions:
- Issue 10 to Issue 15 - Starring Chuck D. Head!
- Issue 34 to Issue 39 - Who Killed Chuck?
- Issue 40 - The Replacement
- Issue 66 to Issue 68 - Monster of the Year
- Issue 69 - The Headless Snowmen
- Issue 70 - Nanny Knows Best
- Issue 71 - The Bride of Chuck D. Head
- Issue 89 - The Pumpkin Chaser
- Issue 91 to Issue 93 - The Legend of Mr Cuddle Bunny
- Issue 94 - The Hungry Guest
- Issue 97 to Issue 99 - Dead!
- Issue 101 - Walls
- Issue 104 - Funny Old Game
- Issue 105 - Wish
- Issue 107 to Issue 108 - Caught By The Prefects
- Issue 109 - Dreaded Poople Plague
- Issue 111 - The Maltese Budgies
- Issue 112 - pin-up
- Issue 113 - Fearless Monster Hunters
- Issue 114 - Chuck and the Cheese Factory
- Issue 116 - Return of the Pumpkins
- Issue 119 - Christmas Carol II
- Issue 120 - Chuck's Savings
- Issue 123 - Love is Blind
- Issue 125 - Dog
- Issue 126 - Mother (mentioned)
- Issue 129 - The Dungeon
- Issue 130 - Birthday
- Issue 131 to Issue 132 - Decap-Man
- Hallowe'en Special - Rooms
- Issue 248 - pin-up
- Issue 257 - Good Luck Chuck
- Sonic the Easter Special - pin-up