The 42-year-old survived a bitter gang feud only to die after cutting his arm on a broken window
Brennan, who died in hospital after suffering a fatal cut to his arm, had survived at least six attempts on his life as part of a feud more than a decade ago.
He was laid to rest following a funeral mass at St. Benedict's Church, Grange Park on Saturday morning.
Speaking from the altar, Brennan’s son said: “I love you, you're the best da in the world,” to which he received a round of applause.
Another family member read a letter from a close friend of John Paul, in which he remembered the 42-year-old as “one of a kind.”
“I seen a lot of men, but you were just different. The charisma and attitude of a winner.”
“I could feel it when I walked proud next to you. I looked up to you my brother,” the letter continued.
“Thank you for the life lessons you gave me, for the changes you brought, for the journey we had and the time we shared and the brotherly friendship that we had.”
Meanwhile, his best friend Anto said the family have suffered a “huge loss” at the death of the family man.
“He passed away on us so suddenly,” he said.
“We’ve been best friends from an early age. We’ve been through the mill together, good and bad times.”
“John Paul was a loving father, he loved his kids to bits. He’d do anything for them.”
Symbols of John Paul’s life presented during the ceremony included a football, glasses, his mobile phone, a paddy cap and a photograph.
A number of male attendees donned matching paddy caps with a white shirt and black tie.
It is understood Brennan was admitted to the hospital on Wednesday after suffering severe blood loss to his arm after he accidentally broke a window in the Cromcastle area of Coolock.
Brennan had recently been living in Greencastle Crescent, Coolock, and had not come to Garda attention recently.
However, he was a major participant in a Coolock feud over the proceeds of a €300,000 robbery which was further complicated by the gangsters fighting over women.
In more recent times, he was the chief suspect for shooting his younger criminal brother Michael Brennan (35) at their family home in Cromcastle Drive, Kilmore, on May 5, 2020, during the height of the first Covid lockdown.
John Paul, or JP as he was known to friends, was never charged in relation to the incident in which his brother was shot in the leg.
In perhaps the most high-profile attempt on the gangster’s life, two innocent men were shot dead when the killers put a car tracker on the wrong vehicle in a planned assassination attempt on Brennan and his right-hand man at the time.
Gardaí believe they were followed by a gang who intended to murder JP Brennan using a tracking device which had mistakenly been put on the car the men were travelling in.
In another attempted murder, a gunman forced his way into Brennan’s then girlfriend’s home, and kicked and fired his way through the house as a one-year-old baby lay sleeping,
Brennan was at his girlfriend’s home at Drynam Drive in Kinsealy, Co Dublin, at 10pm on January 9, 2009, when a gunman kicked down the back door. The target was inside, along with his girlfriend, a second woman and a baby.
The hitman kicked down a locked bathroom door but found an innocent woman inside before locating Brennan, who had barricaded himself into a locked bedroom.
But the gunman fired shots at him through the door. Brennan was hit twice, in the neck and chest, by rounds that also passed through his forearm.
The baby, who was in another room in the house at the time, was not injured. The two women were also unharmed.
The gunman fled and the two women called the emergency services to help Brennan.
Brennan was taken to hospital but made a full recovery.
The incident happened in an area policed by Santry gardaí but it is understood they were not called as ambulance personnel attended the scene and took Brennan to hospital.