So two guys are fighting, and one clearly has the upper hand. He beats the living daylights out of the other guy, but he just won't go down. After one particularly nasty hit, he finally falls. And yet, moments later, he's standing back up again, ready to fight. But suddenly, the fighter realizes something.
His enemy is already unconscious, but is still fighting.
This is when a Determinator goes to the extreme; even once he's been knocked out, he still won't give up. Whether it's grabbing onto an enemy's ankle in their last moments of consciousness, or standing up to fight while knocked out, this goes to show that a character will never, ever give up, even when he can't fight anymore.
Can be used with both heroes and villains; in the case of the latter, the hero will probably consider them a Worthy Opponent.
Compare Attack! Attack! Attack!, where all a character can think of is to keep attacking.
Occurs often in Hajime No Ippo when a fighter — most notably Ippo and Sendo — will continue to box through muscle memory even after he's been knocked unconscious.
Slightly unclear case: in the Lone Wolf and Cub manga, Itto dies standing up while wrestling with Retsudo for a sword in the midst of their Duel to the Death. It gradually dawns on Retsudo that this has happened, so he lets go of the sword and steps out of sword range. After a number of beat panels, Itto finally collapses.
In Magical Girl Lyrical Nanoha StrikerS, Subaru demonstrates the ability to fight even while knocked unconscious. However, this has less to do with her determination and more with her AI-equipped magical Device seamlessly taking control of her body while she is out cold.
In Naruto, during Rock Lee's battle with Gaara, Gaara completely pummels Lee, crushing his left arm and leg in the process. Right before he goes in to make the killing move, Lee's master, Guy, jumps in to save him. However, Lee stands back up, ready to fight once more. When Guy looks into his eyes, though, he realizes that his pupil has lost consciousness, still wanting to fight even after it's over.
In the Raiga filler arc, Lee is able to fight against Raiga while unconscious through muscle memory.
Princess Mononoke featured the detached head of wolf goddess Moro wiggling across the ground and biting the arm off of her Arch-Enemy, Lady Eboshi.
In the Soul Eater anime Maka is knocked unconscious and begins using her previously unknown weapon bloodline abilities to attack in the final battle against the Big Bad. He realises she's even more dangerous in this state and and wakes her up forcing her to invoke The Power of Friendship instead.
In Street Fighter II V, during the final segment of a cage match between Ken and Vega, Ken uses his Shoryuken to send Vega flying into the chandelier above, knocking him unconscious. Vega briefly regains consciousness, long enough to take aim at Ken, and lets gravity do the rest as he passes out; which leads to the following monologue:
Ken: (looks on in amazement, thinking) "You're unbelievable, Vega. Unconscious, yet still you come after me."
During his final battle with Shishio, Kenshin is knocked down but gets back on his feet, and is shown with Blank White Eyes to emphasize how he's really unconscious. One of the observers comments how this shows how determined Kenshin is.
Inuyasha does this once, against Sesshomaru. After allowing himself to be stabbed through the stomach in order to retrieve the Tetsusaiga (for a given value of "allowed"), he quickly staggers and falls to one knee, bracing himself with his sword to keep from collapsing. Sesshomaru notices that Inuyasha's eyes have become unreflective, and that he has clearly passed out; however, as soon as Jaken steps towards him, his grip tightens on the Tetsusaiga and the ground in front of him explodes. Only after they leave does he allow himself to collapse in a pool of his own blood.
Variation in A Certain Magical Index, when Accelerator continues fighting Amata Kihara even after his electrode-transmitter thing runs out of juice (cutting him off from his powers). Without that electrode's help, he is severely brain-damaged, lacking the cognitive function to even walk or speak, or even understand others' speech. He just hates Kihara that much and continues fighting, albeit ineffectively until he Awakens, that is.
One Piece: After Luffy defeats him, Don Krieg takes this a step further by being able to go on a rant about how no one beats him. He's then completely knocked out by his second in command.
Subverted in one issue of The Punisher MAX. Frank shoots Implacable Man Pittsy in the face with a shotgun, after which he takes a few steps forward. Frank says "Reflexes. Gotta be." Sure enough, Pittsy's corpse falls down.
In The Princess Bride, Inigo Montoya's arm seems to block Count Rugen's coups de grace independently. At that moment, "conscious" wouldn't fairly describe Inigo, who seems ready to Go Into the Light.
After suffering a mortal wound, Cú Chullain has himself tied him to a rock so he can keep fighting. Eventually he dies, but when an enemy soldier approaches him to check... Cú Chullain's arm drops and cuts off his hand.
On one memorable occasion, however, Al sold four chairshots as if he were Superman taking a Lex Luthor punch to the solar plexus. Bam. The Road Dogg nailed Al with a chair, and down he went. Amazingly, Al was up within seconds and he was laughing. Bam—another shot, another fall, another laugh. Then another, then another. The boys in the back were irate. When Al came back, I was the first to ask him about his new superhuman powers. Amazingly, Al pleaded innocent. "I don't remember a thing after the first one," He said with a slight slur in his words. "I was knocked out."
Played similarly in the end of Heaven's Feel scenario of Fate/stay night. Shirou overuses Archer'sarm, which turns his body into swords and destroys his mind, and in the end he is able to stay up and destroy Angra Mainyu only through sheer determination.
A rather horrifying real life case was the boxing match between Vince Pettway and Simon Brown. Brown was knocked out with a nasty left hook, collapsed to ground, and while lying flat on his back his arm continued making punching motions into the air. Link for the curious.
Similar but less dramatic was a bout with Jimmy Thunder and Crawford Grimsley. Grimsley was KO'd with literally the first punch of the fight, and medical personnel rushed to the ring to help him. A semi-conscious Grimsley had to be restrained from punching at the medical people attending him while still on the canvas. Link here.