A renegade sniper has been striking fear into the hearts of terrorists in Mosul — picking off local jihadis one by one, including an ISIS executioner moments before he was to behead a teenage boy, reports said.

The mysterious marksman — dubbed the “Sniper of Mosul” — is believed to be behind shootings in four separate neighborhoods of the Iraqi city, though officials think he could be receiving help from other sharpshooters, according to the Daily Star.

He has been hunting down militants in broad daylight, with the most recent hit unfolding during a public beheading.

Iraqi media outlets Monday reported that the enigmatic sniper had killed an Islamic State executioner just seconds before he could take the life of a local teen who was accused of supporting resistance movements within Mosul.

His bullet struck the ISIS savage just as he was taking aim at the boy’s neck, sources said.

The attack prompted the terrorists to frantically open fire and scatter, as they attempted to find cover. The recent shootings have already left a “number” of jihadists dead, according to Al Sumaria News.

Despite the sniper’s efforts, sources said ISIS fighters shot and killed the boy before he was able to escape.

The gunman and/or gunmen have been targeting extremists in Mosul for several days as Iraqi-led coalition forces continue their battle to retake the Islamic State stronghold.

“The emergence of the ‘Sniper of Mosul,’ as the residents call him, increased the pace of the popular resistance against the ISIS,” Al Sumaria News reported. “The presence of the sniper in four neighborhoods emphasizes that there are many snipers and not only one.”

Some believe the “Sniper of Mosul” could be part of an elite special forces team — though it is unclear whether they are Iraqi or allied soldiers.

While the man is surely making a name for himself, he isn’t the first to make headlines for taking out members of ISIS.

In January, another mysterious marksman — dubbed the “Daesh Hunter” — had extremists on the run in Libya after he assassinated a few of the group’s terror chiefs.

At least three Islamic State leaders were killed by the lone sniper over a span of 10 days, sparking a “state of terror” in the ranks, sources said.