Canis Wolfborn, also known as Growlthroat, the Feral Knight, Fangrider, or even Dog Wolfborn, is a crazy fucker that rides a giant fucking wolf the size of a mastodon into battle. And is followed by a bunch of fucking Fenrisian Wolves that he can command. By barking at them...yeeeeaaaaah. He is a warrior of the Space Wolves Chapter.
Canis was said to have been raised by a she-wolf as a young boy when he sought shelter in the cave she was in and after a while, grew up and hunted with his new family, wolf tendencies included. He was recruited into the Space Wolves after a Wolf Lord named Harald Deathwolf discovered and challenged him to a grueling duel, which Deathwolf eventually won. Rather than put him down, he was brought to The Fang and made into an Astartes. Doesn't this backstory sound vaguely familiar?
Many people consider him to be everything that's wrong with the 5th edition Space Wolves Codex (AKA: an unhealthy amount of Wolf EVERYWHERE, to the point where the Space Wolves sound more like space furries instead of werewolf vikings in SPEHSS). Other people consider him to be an absolute badass rivaling Ulrik the Slayer or even Bjorn himself. Make of that what you will. Most people agree that his name is goofy however, not just because it's "Dog Wolfborn", but also because Canis is a Latin word rather out of place on a Space-Norseman's name. It'd be like an Ultramarine named Sven Ulrikssen, it's just weird.
He got killed by a Khorne herald in warzone Fenris. No he didn't, he was saved at the last moment by his wolf.
On the tabletop
Canis is quite the interesting chap. Like all wolves he has acute senses and ATSKNF, plus counterattack, rampage, and independent character. If he gets charged his Born of Wolves rule allows him and any wolves (actual wolves, not space marines) in his unit to reroll to-hit rolls. Nice, I guess? His warlord trait, Saga of the Wolfkin, gives all Cavalry and Beasts in his detachment Stubborn, plus any Beast or Cavalry unit within 12" of him gets Furious Charge until the end of that turn. Gear-wise he brings power armor, two wolf claws, a bolt pistol, frag and krak grenades, and mounts a Fenrisian wolf. He has a few issues. #1, no invuln and shit armor. His T5 will help a bit with survivability, as will his great mobility, but any character with better initiative and a power sword will fuck him up. Somewhat less problematic but more confusing is his BS of 2. The fuck? Orks are laughing at your aim dude. This isn't really a problem because you'll never be shooting with him, but one has to wonder what horrible Tzeentchian curse he suffered to have a fucking BS of 2. As far as tactics go, he's a bit of a one trick hat but he's damn good at what he does. To put it simply,
Step 1. Stick Canis in a unit of Thunderwolf Cavalry and Puppies.
Step 2. Use cover and LOS to avoid getting shot until you can charge.
Step 3. Charge.
Rinse and repeat.