Few people know this about Uther, but he actually rerolled pally from priest.
Uther was a cleric of the Holy Order of Northshire as the First War started. A young man of 20, an apprentice to the Archbishop Alonsus Faol. Uther watched as his order was almost totally wiped out and was forced to retreat with the rest of the survivors of Stormwind to Lordaeron, and he came to believe that the error of the Clerics was in attempting to fight the brutality of the orc invaders with faith alone. Working with Faol, Uther helped recruit others from the old Holy Order and founded the Knights of the Silver Hand, becoming the first leader of the order. The first Paladin in Azeroth.
Uther fought throughout the Second War: It was Uther who helped bring the treachery of the Perenolde family to light and exposed the lord of Alterac as a traitor to the Alliance itself, and he was on the front lines when Gul'dan betrayed Orgrim Doomhammer and took half of the Horde's forces across the sea to the Tomb of Sargeras. While the Alliance forces weren't sure what was up, they did know opportunity when it presented itself, and soon they'd driven the orcs back to the foot of Blackrock Mountain itself. During that battle Anduin Lothar died, Orgrim Doomhammer was defeated, and Turalyon, one of Uther's fellow paladins, bestowed the name 'Lightbringer' on the first of his order. Uther even led the Alliance forces that ultimately broke the back of the Burning Blade Clan near the end of the war.
All of his heroism during and after the war caused him to be seen as not just the first, but also the best of the Knights of the Silver Hand. Still, even then he could make a mistake: it was Uther who performed the ceremony that supposedly cut off Tirion Fordring from the Light after Tirion attempted to defend the orc Eltrigg but the Light did not forsake Tirion. Either Uther wrongfully believed he could remove a paladin's connection to the Light and was thus mistaken or he went along with a judgement that could not be enforced and was thus guilty of deception. Either way, it was a small mistake that was the harbinger of mistakes to come.
As Uther's reputation spread, he became mentor, instructor and friend to Prince Arthas Menethil, heir to the throne of Lordaeron. Uther was the future king's friend and teacher, and when the spirit of the orc shaman Ner'zhul sent his minion Kel'Thuzad to spread the Plague of Undeath through the land, it was while Uther and Arthas were facing Jubei'Thos and his Blackrock Clan. Entrusting Arthas with the task of finding and defeating the Plague, Uther ended up having to reinforce the town of Heathglen when tainted grain transformed the people into mindless undead. He followed Arthas to Stratholme, and their ultimate parting of the ways, when Arthas found out that the people of the city had already eaten the grain and would therefore become undead . The future King of Lordaeron ordered his mentor and friend to kill the people of the city in order to keep the plague from spreading, but Uther refused to kill men, women and children who were not currently undead. Enraged at Uther's refusal, the prince declared the Knights of the Silver Hand disbanded (which was not in his power to do) and Uther guilty of treason. He then purged the town himself with those soliders personally loyal to him.
While Arthas was running after Mal'ganis and his own destiny in Northrend, Uther returned to speak to King Terenas, who far from supporting his son's battlefield pronouncements instead agreed with Uther that the young prince was out of control and sent an order to recall him. What happened next... Arthas' treacherous burning of the boats, the fall to darkness and rise as a death knight... Uther could know nothing of. All he knew was that he had done his duty by his king and nation, and so, when Arthas returned he may well have hoped that the young man had finally come to realize the folly of his actions.
Instead, Uther heard of the death of King Terenas as the hands of his own son as the Scourge erupted throughout Lordaeron itself. Uther, grief stricken and still attempting to do his duty to his fallen King, would stand watch over Terenas' ashes in Andorhal until, as he may well have suspected, Arthas came for them. The mentor met his student in combat and, although he fought valiantly, fell. Whether Uther secretly desired death rather than witnessing the full depths of Arthas' corruption or whether he could have defeated his fallen friend if given a chance to face him in fair combat we'll never know.
The loss of Uther, as well as other leading paladins such as Gavinrad, Turalyon (lost in the Alliance expedition to Draenor years earlier) and Tirion (exiled for his refusal to betray Eltrigg) effectively gutted the Knights of the Silver Hand and ended the existence of the force of paladins as a unified whole in service to the Alliance. While they themselves would still fight against the Scourge and the Burning Legion, it was Arthas' betrayal and the destruction of the order that would allow the existence of the Scarlet Crusade. It would have been impossible for an order of paladins devoted to vengeance to have existed while the man who swore that 'Vengeance cannot be a part of what we must do' still lived.
Uther was among the most steadfast, brave and heroic people Azeroth ever produced. He was not perfect: some still blame him for his errors in training Arthas and his decision to banish Tirion from the Order was clearly not one the Holy Light itself agreed with, but Uther strove to the utmost to defend his people and his nation. Whatever your feelings about paladins, about honor, or about the factions in Warcraft, there's no disputing that Uther the Lightbringer sought every day to earn, not merely wear, the accolades he was given, and his failures stemmed from the very source of all that was noble in him, his unwillingness to turn his back on his fellow man or assume the worst of anyone.
Yeah, I know this one hasn't really been very funny. I can't make fun of Uther, sorry. He's just too cool.
We see Uther's spririt in World of Warcraft as part of rival horde and alliance quest chains. The horde one comes from Melhar Dawnblade at the Bulwark in Tirisfal Glades, while if you're alliance you can look up Anchorite Truuen at Chillwind Camp. If you haven't done either of these quests I recommend doing it just from a lore perspective.
If this was an afterschool special I'd be telling you to read more about Uther at your local library. Since this isn't, I'll point you to some online resources instead: the always wonderful WoWWiki article on Uther, Blizzplanet's lovely transcriptions of in-game books mentions Uther here and here and also here.
Next time I'm up we'll see a bit of a change of pace.