Variations on OODA loop interruption. All of these only provide a brief, half-tempo hesitation, and as such have to be done immediately (i.e. you can't freeze someone, see that it works, and then start the action. Waiting to see the response negates the effect. Targetting is still possible, though)
Distract: Make the opponent observe, orient, and possibly decide about some irrelevant stimuli. Easy example of this is dropping something before entry. The opponent sees it drop and has to process what that means. The fact that the stimuli gets into their brain means you at least steal some of their brain processing time even if they decide to ignore it. Fails if they don't notice it at all, which is possible depending on their tunnel vision. I file the "am I hurt?!?" reaction in this category, where people feel contact and attempt to decide if they are seriously injured, or if the hit was sufficient for scoring or what have you. Can get a bonus confuse effect too, as in the showing a weapon, brandishing it, dropping it and attacking with something else.
Confuse: Make the opponent fail to complete the orient phase. Basically, this is a hesitation you get when the opponent simply cannot understand what is happening and, instead of ignoring or acting, attempts to figure it out. This is what makes a wide variety of "tricks" work- they're just so weird the opponent doesn't have a response. Guru Mike demonstrates this by suddenly making like he's gonna kiss the guy he's fighting while grappling, then unleashing a flurry of elbows as their brain shuts down.
Freeze: Interrupting the loop by providing new information just before the opponent is about to act. Requires being able to read body language and thought process. Usually I do this by amping threat- often just bending knees. From the outside, it appears as if I simply attack and the opponent does absolutely nothing. What is actually happening is they have prepared to attack, and, the instant before they start to move, I suddenly appear to change. They abort and try to figure out if this change is important, and get hit. Good fencers can do this to inexperienced fencers almost at will. I've seen coaches who don't get it yell at their students, "Don't just stand there! Do something!" as a more experienced fencer does this to their student over and over again. It's something that's being done to them, the more they try to do the "right" thing the worse it gets. Can be defeated by the opponent not caring what you do, so it won't work on the threat-blind.
Stutter: Like the freeze, except you initiate it. You start moving, the opponent sees the movement, interprets it correctly, begins their reaction, you stop moving, the opponent sees the stop and starts trying to abort their reaction, you restart the motion, they're still trying to stop, etc. Basically compounds the idea of "action beats reaction", messes them around until you're well ahead. Depends on the opponent reacting in a way that they can recognize as nonoptimal- for example, moving the blade to block, when they realize that doing so would create an opening. If they don't recognize a problem, or if the reaction is safe no matter what (retreating instead of blocking, for example), stuttering doesn't work. Opponents who have been trained that there is one correct on-guard position that they should always be in are particularly susceptible to this.