Ursai

Ursai are large, dark, bear-like creatures of Grimm.

Appearance
They appear much like the new Beowolf, with black fur and bony spikes on their backs and arms, as well as white, bone-like masks with red detailing, but are much larger and stockier.

There are also larger Ursai in the world, known as Ursa Majors, and one was seen living in the Forever Fall forest. Like its smaller counterpart, it has bony spines and a skull mask with Grimm markings, but also possesses many bony plates on its back and limbs.

Volume 1
In The Emerald Forest, while Yang Xiao Long is looking for someone in the Emerald Forest, she hears something in the bushes and wonders if it is her sister, Ruby Rose. However, two Ursai appear out of the bushes and attack. Yang fights them off almost playfully until one cuts off a tiny strand of her hair.

Yang goes berserk and punches one of the Ursai multiple times, launching it through a group of trees. She turns to confront the other one, but Blake Belladonna manages to kill it with a single strike from Gambol Shroud.

In Players and Pieces, an Ursa rampages through the forest until it is in sight of Blake and Yang. The Ursa then collapses due to it being shot in the back, revealing that Nora Valkyrie had been riding it. The girl is left apparently saddened that it is "broken" and looks over the body to see if it was still alive.

In Forever Fall, Pt.2, an Ursa Major comes out of the woods and attacks Team CRDL and Jaune Arc. It appears to focus on Cardin Winchester due to the Red Sap on his body. Despite the fact that Cardin bullied him, Jaune was willing to help his classmate by defending him.

After a short battle, with Pyrrha Nikos using her Semblance to assist, Jaune defeated the Ursa Major by decapitating it.

Volume 2
In No Brakes, an Ursa can be seen behind a Creep in the tunnels leading to Vale. Later, the Ursai, including some Ursa Majors, enter the city when train breaks the barrier to Mountain Glenn.

In Breach, Jaune once again fought an Ursa, but unlike before, he managed to take it down on his own after a series of blows. Meanwhile, an Ursa Major was killed by Emerald Sustrai with her pistol scythes. Another was destroyed by Fox Alistair.

Volume 3
In Beginning of the End, Ursai are among the Grimm that head towards the city of Vale, drawn by the negative emotions there.

Abilities & Powers
They are first shown in The Emerald Forest attacking Yang, though they don't manage to land a strike on her. It seems that they are slower, but possibly stronger than Beowolves, being able to shrug off several blasts from Ember Celica. They seem to prefer attacking in pairs, suggesting ties of pack or familial origins when hunting prey.

However, the Ursa Major that appeared in Forever Fall, Pt.2 was far larger and stronger, effortlessly overpowering Cardin and managing to endure a direct slash to its unarmored belly from Jaune's sword. It was only defeated when Jaune decapitated it.

Trivia

 * Their name comes from the Latin word for bear.
 * Although ursae is the Latin plural for the word ursa, the plural is given as "Ursai" according to in-episode captions and published scripts. The word probably does not follow the standard plurals because Latin doesn't exist in Remnant.
 * The fact that Yang fights these bear-like creatures in the woods could be an allusion to the fact she is based on Goldilocks, who also encountered bears.
 * The name "Ursa Major" is likely a reference to the constellations of Ursa Major and Ursa Minor.
 * Ursai are the only known type of Grimm that have more than one named variety.
 * Russel Thrush's lines referencing Ursai from Forever Fall, Pt.2 were remixed into a techno song and music video, "That's a Big Ursa!", that is featured as an easter egg on the Volume 1 DVD. In the video, two Ursai can be seen dancing alongside Russel at Junior's club.