Big things are happening on TV Tropes! New admins, new designs, fewer ads, mobile versions, beta testing opportunities, thematic discovery engine, fun trope tools and toys, and much more - Learn how to help here and discuss here.
Rafael Sabatini's famous pirate, Captain Blood, started his career as Doctor Blood. It works either way! He was not bloodthirsty at all, and was a complex and sensitive man, so his name had a touch of irony to it... Which was completely lost in the movie, turning him into an uncomplicated badass with an appropriate name.
The Bloody Baron from the Harry Potter series, as well as a vampire named Sanguini.
The crimelord who forms the main antagonist in Gene Wolfe's Nightside the Long Sun goes by the name of Blood. (In their city men all have single names that refer to animals or animal byproducts, like the protagonist Silk and his student Horn, but Blood is still an alarming name even in context.)
Averted in the second series of Welkin Weasels novels, where one of the main characters is named Bryony Bludd, which is lampshaded by (wouldn't you know it?) a vampiric stoat. It's still a Meaningful Name, though; she's a veterinary surgeon (which within the series actually means a doctor to her fellow Talking Animals).
The evil-sounding connotations of Blood as a name is what led a young, babyface pro-wrestler to switch from his real name, Richard Blood, to the stage name Ricky Steamboat (arguably the only example of a wrestler having a more Badass real name than stage name)
Final Fantasy XIII's Fang: Wields a dual headed collapsible spear that can be separated and dual wielded. She's naturally the best attacker of the game Plus she had turned into Ragnarok centuries ago and made that huge hole in Cocoon's shell you always see.
Only known name of a revenge-driven serial killer in Fullmetal Alchemist who is out to get every single state alchemist and all those who get in his way via alchemical brain explosion. He's so effective at this that all high-ranking officers temporarily abandon their HQ in Central City where he was spotted and head out to the Eastern boondocks.
Subverted in John Ford's classic, The Searchers: Cicatrice, aka "Scar," does indeed commit a heinous act in killing a settler family and kidnapping the two daughters...but after that he spends his time either oblivious to (as in, living his life and leading his tribe) or running from the man who spends years hunting him down, Determinator Ethan Edwards.
Blitzwing, Thunderwing, Darkwing, Wing Dagger, Wing Saber, and about a dozen other Transformers with "wing" in their name. Although the Decepticon Darkwing's name is less threatening, due to the unfortunate coincidence of being shared with a Disney duck character.
Naruto has the Nine Bijuu, aka Tailed Beasts, with immense amounts of power that increase exponentially with each tail. Their names are, in order of tails: Ichibi (a sand tanooki), Niibi (a fire-cat), Sanbi (a genjutsu turtle), Yonbi (a lava-breathing gorilla), Gobi (a dolphin-horse), Rokubi (a slug), Nanabi (an armored rhinoceros beetle), Hachibi (an ox with an octopus behind), and Kyuubi (a Kitsune)
The short story "Satan's Incubator" by Randolph Craig has a main character named Dr. Skull: This initially seems like an aversion, as he's initially portrayed as a kindly, well-respected and elderly doctor... Then it turns out Dr. Skull is wearing makeup and a wig to disguise his appearance, and is but one of two alter-egos of the actually young and agile main character - The other is a heroic but deadly vigilante known as The Skull Killer.
The "Argus Monitor" is a medium-size lizard with a pattern that resembles eyes, which is why it was named for this mythical character. It's almost a subversion, though, since other monitor lizards are much bigger and more formidable than it is.
In the episode "The Headband" of Avatar: The Last Airbender, Sokka briefly wears a fake Badass Beard and adopts the alias "Wang Fire" (yes, Wang Fire, on a Nickelodeon cartoon) while posing as Aang's father. note Sokka has worn the beard on several occasions after this, including a mini-comic in which he infiltrates the Fire Nation military under the name Wang Fire. The comic ended with him pretending to be killed while taking out a Waterbender and Earthbender, and being remembered as a hero. Although not particularly intimidating in the show, Wang Fire has become a Memetic Badass among fans, identified as the god of manliness and beards and as a separate entity from Sokka.
The Crimson Chin from The Fairly Oddparents. Timmy also adopted the name "Cleft the Boy Chin Wonder" (as in "cleft chin") while serving as the Chin's sidekick.