Beowolf

Beowolves are large, dark, werewolf-like creatures of Grimm.

They are the first Grimm seen in the series, making their first appearance in the "Red" Trailer, before returning in the episode "The First Step, Pt.2," during the show's main run.

Appearance
Beowolves resemble the traditional, bipedal forms of lycanthropes, more commonly known as werewolves. They stand on their hind legs, albeit with a slouch, and are extremely muscular. They have pitch-black fur and red eyes. Their heads also appear to be made out of bone and display skull-like features.

They appear to have protrusions made of bone along their back and arms. They have long, sharp claws, with which they lunge at Ruby Rose during the "Red" Trailer. They have enough strength to knock back Ruby with a swiping motion.

Just like the Ursai, Beowolves can vary greatly in size. The average Beowolf is about the size of a normal human, but as they age, they can grow to be more than twice the height of a human.

Ruby Rose
Beowolves are among the three species of Grimm that are shown as silhouettes in the opening narration.

"Red" Trailer
The Beowolves confront Ruby as she is walking through the Snowy Forest. They rush at Ruby, but she dodges and unsheathes her weapon, Crescent Rose, and begins to attack them.

After firing a few bullets, Ruby fully activates Crescent Rose so that she can use its scythe function to strike back at the Beowolves in a series of vicious attacks. Eventually, one Beowolf puts Ruby on the defensive, but only temporarily, as Ruby switches ammo and quickly goes back on the offensive, finishing off the remaining Beowolves.

The Emerald Forest
The Beowolves appear in the Emerald Forest as Ruby and Weiss Schnee walk through it. Weiss, separated from Ruby, prepares to attack the Beowolves. However, Ruby suddenly reappears and hits one of the Beowolves with her scythe. This causes Weiss to misfire when she moves to stop herself from hitting Ruby, resulting in a small forest fire being started.

This distracts Ruby long enough for the Beowolf she had initially attacked to hit her into Weiss. Ruby plans on continuing the fight with the Beowolves, but is forced by Weiss to flee when the fire spreads. The Beowolves seem upset by the fire, as they howl into the sky and begin to scatter.

Search and Destroy
A Beowolf pack is encountered by Team RWBY and Bartholomew Oobleck during "Search and Destroy." They serve as fodder, as Team RWBY proceeds to slay them all, while talking to Oobleck about why they wanted to be Huntresses.

Mountain Glenn
A lone Beowolf is seen briefly from the view of Ruby's weapon's scope. It scrounges around aimlessly, however, it isn't hostile towards Ruby, despite staring right at her.

No Brakes
Beowolves are among the many Grimm infesting the underground tunnels in Mountain Glenn, and were thus free to enter Vale when the barriers were destroyed by the crashing train.

Breach
The Beowolves that entered the city were dispatched by Teams RWBY, JNPR and CFVY, with help from the Atlesian military, Zwei, Dr. Oobleck, Peter Port , Glynda Goodwitch, Mercury Black and Emerald Sustrai.

Abilities and Powers
They are first shown in the "Red" Trailer as Ruby's opponents. They attack like a regular wolf would, with clawing and lunges, and no special skills or abilities demonstrated as of yet.

Their behavior varies depending on age. Younger Beowolves do not act like normal wolves, lacking any sense of self-preservation. They relentlessly attack no matter how hurt they are or how many of their pack members are slain. Older Beowolves gain a sense of self-preservation like normal wolves and eventually become more intelligent than them, observing their allies, retreating when needed and developing strategies for future encounters against Hunters and other threats.

They are extremely agile, as seen when they stalked Ruby through the Snowy Forest, as well as in their subsequent fight with her.

Trivia

 * According to Miles Luna, Rooster Teeth Productions is "very proud" of the name "Beowolf."
 * According to Monty Oum, Ruby fighting wolves was intentional as he wanted people to see the obvious reference to Little Red Riding Hood.
 * The Beowolf name originates from the Anglo-Saxon epic poem Beowulf, which is about a great hero who slays many monsters.
 * In the "Red" Trailer, the Beowolves appeared as black wolf shadows because Monty was working on the trailer by himself. Patrick Rodriguez, one of the concept artists and character designers for the series, later redesigned the Beowolves.
 * During RTX 2014, Monty stated that the Beowolf was considered "the slime" of the Grimm. This could mean they are, if not already, the lowest tier of the Grimm species.
 * In the sponsors-only demo of the video game RWBY: Grimm Eclipse, a White Beowolf appears once the normal Beowolves have been defeated. No official comment has been said regarding it, nor has it appeared in the show. It presents superior strength and intelligence compared to the "normal" Beowolves, as it will block and dodge attacks. There is no evidence at this time that this Grimm will become canonical within the series.