Valkyrie

Brunnhilde is the leader of the Valkyries.

Biography
She was seen with Lady Sif and the other surviving Valkyries in rescuing Ant Man and Wasp from Ymir and his Frost Giants in Jotunheim.

Then she was seen flying into battle against Loki and his dark forces riding a pegasus with Ant/Giant Man in his Asgardian battle armor riding at the back.

During the battle, she was knocked out by a Frost Giant only to be saved by the Hulk

After the battle, she was seen among the Asgardians praising the Avengers in saving the Nine Realms from Loki's grasp.

Powers and Abilities
She is a skilled fighter capable of holding on her own in battle. She can even ride a pegasus.