Nickolas Benjamin 'Nicko' Heap is the sixth son of Sarah Heap and Silas Heap and lived in The Ramblings with Sarah, Silas, his brothers, and Jenna Heap. He is two years older than Septimus and works as a Junior Apprentice for Jannit Maarten (who works at the Docks) with fellow Apprentice, Rupert Gringe.
Nicko has the Heaps' signature straw-colored, curly hair, and gained his green eyes once he started learning Magyk. Nicko has large eyes. After becoming Boatyard Junior Apprentice he wore some of his hair in braids, a common fashion in the boatyard.  He is very skilled at sailing boats and does not show too much interest in Magyk or becoming an Ordinary Wizard. Nicko and Septimus are very close, with Nicko often believing Septimus at times when no one else will. He is claustrophobic and fearful of confined spaces, though he seems able to control this fear to an extent when he has to. He also has some romantic interest in Snorri.
When he was 12 he went with Silas to deliver a present to Jenna in the Wizard Tower. The Assassin comes after them and Nicko flees with Silas, Jenna, Boy 412 (Septimus Heap), Maxie, and The ExtraOrdinary Wizard, Marcia Overstrand. He skillfully sails Muriel, a little fishing boat, to the Marram Marshes where they hide with their Aunt Zelda in Keeper's Cottage. He helps Jenna and Boy 412 (later revealed to be Septimus Heap) to get Marcia back from DomDaniel and is present at Septimus's Apprentice Supper and when Septimus discovers who he is.
Nicko is now the Boatyard Junior Apprentice to Jannit Maarten. He goes with Septimus to rescue Jenna from Simon Heap. To find out how to do this he meets the Wendron Witches' Witch Mother and listens to her advice along with the rest of his brothers. He bursts out laughing when she says her third message: 'Do not go to the circus', much to the embarrassment of his closest brothers, Jo-Jo and Septimus. He goes with Septimus and Wolf Boy to the Port, and to the Marram Marshes. Nicko travels back in time with Jenna and Snorri Snorrelssen to rescue Septimus, who was taken back five hundred years into the past by the Alchemist Marcellus Pye to become his apprentice. When Nicko, Snorri, and Jenna find Septimus, they convince Marcellus to open the Great Doors of Time so they can return to their proper time. When Snorri doesn't make it to the doors, Nicko decides to stay with her and they become stranded in the past.
After becoming trapped five hundred years in the past, Nicko and Snorri head to the House of Foryx in hopes of being rescued. They are trapped there for a fair amount of time (500 years) and are eventually joined by Septimus, Beetle, and Jenna, who had come to save them but are also trapped when Beetle - who was supposed to wait outside - falls over the threshold and the door closes behind them. All five then had to wait for someone else to rescue them.
Nicko and Snorri don't appear in Queste until close to the end but they are a driving force in the overall plot and play a large part in the final chapters. In their attempts to escape the House of Foryx they try to send messages for Marcia using a door that Septimus recognizes as a mirror of that of the ExtraOrdinary Wizard. Meanwhile, Jenna is being harassed by one of the House Guardians who is demanding the key to the Queen's Room (which she wears around her neck). When it becomes clear that she is trying to keep them from leaving, Nicko loses his temper and breaks her arm to escape her. After this, he chooses to leave the House no matter which time he enters but as he throws open the door he finds Marcia and Sarah Heap waiting outside, allowing all of them to leave into the correct time period.
Nicko, Snorri, Jenna, and Beetle go to the Trading Post and stay on the Cerys, Milo Banda's ship. Septimus arrives to take them home on Spit Fyre, only to find them preparing to sail home on the Cerys. Beetle decides to go with Sep on Spit Fyre and convinces Jenna at the last minute. Nicko stays with Snorri on Milo's ship and sails it at night. He followed Milo's instructions and sailed toward the Light, which had been put up to trap them. The boat is besieged by Skipper Fry and the Crowe twins. They were pushed into the cargo hold by Septimus and Beetle, and released the warrior jinn, which was kept in a battered chest that Tertius Fume had told Milo about. Jim Knee freezes the jinn and everyone sails to the Port on the Cerys. After Nicko returns home, he is happily reunited with his family.
- Nicko gained a crush on Snorri Snorrelssen in the time they spent together in the House of Foryx, which supposedly came to an end after Snorri left the Castle. By Pathfinder, however, they are reunited and engaged.