I've already posted about Henry Howard Heyman or Lewis, and (briefly) Frank (or William) St. Clair. Here are some others.
Unknown “black man”.
Executed: William Good (Wellington) 17 June 1850
"The prisoner then walked with a firm step to the front of the scaffold, and the executioner, (a black man who arrived in the colony about two years ago) having adjusted the rope round his neck the drop fell, and a few short struggles terminated the prisoner's existence."
Unknown prisoner at Mt Eden stockade (in 1863). Possibly James Stack.
Executed: Richard Harper (Auckland) 22 September 1863
Executed: Alexander McLean (Auckland) 21 October 1864
"The executioner in the present instance was a prisoner in the stockade, who was offered a sum of money and a reduction of his sentence, to perform the duties of Jack Ketch. He was completely disguised in person—having a soldiers' lone frieze coat on, his face and head covered with black crape, and a slouched hat drawn close over it. On retracing his steps from the scaffold after the execution, and crossing the yard for the purpose of entering the gaolers' room, to wash and divest himself of his disguise, he appears to have been recognised from some peculiarity in his gait, by his fellow prisoners, who had been watching the proceedings, as far as possible, through the gratings of their respective cells. His appearance was the signal for a perfect Babel of yells, hooting, curses, and the most terrible threats of vengeance. During the course of the day he was removed to another place of keeping, to be out of reach of injury from his fellow prisoners."
John Thomas
Executed: Ruarangi (Auckland) 18 April 1864
Executed: Nikotema Okoroa (Auckland) 18 April 1864
"The hangman, whose head and shoulders were completely covered by a black veil, and who, judging from the appearance of his hands, was a coloured man, at length advanced to perform the duties of his office. He shook hands with the unfortunate men, and on the signal being given let down the drop."
"The man who acted as hangman at the execution of Ruarangi and Okeroa is a man of color, who many persons may have frequently seen walking about the sheets of this town. He no doubt was well rewarded for undertaking the disagreeable task, but subsequent events have proved that he did not make a good use of his money, for at an early hour last evening he was so intoxicated that it was found necessary to put him in the lock-up."
"The mulatto who officiated as hangman at the execution of the two Maoris on Monday last (whose name is John Thomas), has, we understand, been apprehended on a warrant taken out by Paul, the native chief, for using threatening language to him. It appears that on Monday last, after he came back to this town from the Mount Eden Stockade, he appeared ambitious to make himself known as the hangman, and very unprovokedly used language of a very insulting description to every Maori he met, and among others to Paul, the native chief. The latter very justly is desirous of obtaining satisfaction for the insult offered to him, and has accordingly taken out the warrant. It will be seen by our police report that the offender was brought before the magistrate yesterday morning, and released on the condition that he should leave the town. He has, however, been reprehended. On offering the insult to Paul to which we have alluded, some Europeans were by, and justly resented the outrage upon our friendly ally, who on all occasions conducts himself as a gentleman."
"John Thomas, the man who officiated at the late execution, was brought up at the Police Court yesterday, before the Resident Magistrate, to answer to the charge brought against him by Paul, the native chief, and was bound over to keep the peace, but as he was unable to find the necessary sureties he was sent to gaol."
Unknown prisoner, Mt Eden gaol
Executed: James Stack (Auckland) 7 April 1866
“The person who undertook the office of hangman was undergoing a short sentence of imprisonment, which, we believe, was within a few months of having expired, so that his object was not so much the liberty to be granted to him, as the £10 he was to receive. He is said to have had considerable practice in the horrid work in another part of the world.”
A man of “very advanced age”
Executed: Robert Wilson (Nelson) 20 December 1867
“The man who performed the odious office of executioner was, we are informed by the gaol authorities, not a convict, but a man of very advanced age, who had volunteered his services, and who showed far greater signs of trepidation than the unfortunate prisoner himself.”
A Rangiora resident
Executed: Simon Cedeno (Lyttelton) 5 April 1871
Executed: John Robinson Mercer (Lyttelton) 7 May 1875
“The hangman was the same man who hung Cedeno, and who resides at Rangiora.”
David Marshall
Executed: Hamiora Peri (Wellington) 16 November 1869
Executed: Tuhiata (Wellington) 29 December 1880
"Tuhi was placed in the centre of the drop and handed over to the executioner. This functionary—David Marshall by name— is the person who eleven years before had performed the same office upon the occasion of the execution of Hamiora Peri for murder. He is a little, spare man, with gray hair; long white beard; thin, wizen, and anything but pleasant features. He made no attempt to disguise himself in any way, and seemed quite at home in the performance of his hideous task."