General aviation pilot reported an NMAC during final approach with a helicopter that crossed the runway without communicating. Pilot took evasive action to avoid a collision.

Narrative

I was approaching to land on Runway XX at ZZZ Airport at XA:11 at night. I self announced on the CTAF frequency my position on downwind; base; and final. I heard an aircraft self announced that an Augusta was taxiing out. I was not familiar with an Augusta until later.While on base; I observed the aircraft taxiing at ZZZ to the runway. As I rolled out on final; I self announced on final. The aircraft was not taxiing up to the beginning of Runway XX; but instead to the Taxiway 1 entrance to XX approximately 1500ft down the runway. It appeared that the aircraft was about to taxi out onto the runway while I was on short final but it came to a stop.I could see a red blinking light from the otherwise invisible aircraft slightly off from the runway. I surmised that the blinking characteristic of the light meant that it was a rotating beacon and therefore indicated the back of the aircraft and not the front. The red beacon was approximately halfway between the main parallel Taxiway (2) and the runway. This made it evident that the front of the aircraft could be on or just short of the runway.I could not see the hold short markings at the airport but I was certain that they could not be that close to the runway. I inferred that the aircraft was across the hold short line and possibly on the runway itself. Not knowing if the aircraft would pull out suddenly and occupy the runway; I elected to go-around. I announced on CTAF that I was going around. When overflying the runway and climbing; I clearly observed that the aircraft was a helicopter and that the entire helicopter was past the hold short line and right at the runway edge.It is possible that the blades of the helicopter were across the runway edge and even more likely that rotor wash from the helicopter was extending right into the runway touchdown zone. This would be a dangerous place to be low and slow to land.I announced turning cross wind and stated that the go-around was due to another aircraft entering the runway.I heard no further radio calls from the Augusta. Turning from crosswind to downwind; I observed the Augusta on a low tight crosswind leg over the center of the airport. Instead of flying the typical right hand pattern for helicopters; the Augusta was making a tight left-hand pattern inside of my pattern. However; the airspeed of my Mooney was significantly higher so I was catching up to the Augusta turning crosswind to downwind without announcing. The Augusta still remained below. However; this is a dangerous situation because the helicopter is not likely to be able to see up while I certainly cannot see below.To avoid overflying the climbing Augusta; I was forced to perform an evasive 360 degree turn in the direction of the runway from downwind. I did not hear the Augusta make any radio calls except for the initial announcement about taxiing out.So; in the rush to depart; the helicopter created not 1 but 2 close calls. The first by stopping fully across the hold short of the runway while an airplane was on short final and the second by turning and climbing inside the traffic pattern of another airplane.Night conditions were a factor in not being able to clearly see the exact location of the helicopter or the exact location of the hold short lines. However; due to the early sunset time; night fatigue was not an issue as it was still pretty early into the evening.Due to repeated avoidance of the Augusta helicopter; the outcome was favorable. However; this runway incursion at night posed a dangerous situation for a pilot that might not have realized the proximity of the helicopter on the ground to the runway while across the hold short. It is easy to assume that if you see an aircraft on the ground stopped before the runway; that they are in fact behind the hold short at a safe distance. I am disappointed in the lack of professionalism of the helicopter crew not only in crossing the hold short but also failing to notify me of the dangerous situation this runway incursion created.