Little Oars Jr. is a pirate captain who is the descendant of Oars and an ally of the Whitebeard Pirates. He is among the several New World pirates aiding the Whitebeard Pirates in saving Ace.

Like Oars, he is a giant larger than regular sized giants. He also wears three skulls together, except as a necklace. His overall shape and silhouette resembles Oars. Among his effects is notably a gigantic kasa that Ace made for him.

Oars Jr. seems to be a very good person at heart. As shown in flashbacks, he was very carefree, and appreciated little things, such as the straw hat Ace made for him. He is also shown to be very determined, as he went straight through the enemy lines to rescue Ace, even continuing on after one of his legs was lopped off by Doflamingo.

Oars Jr. has had some positive relationship with Ace in the past. The most prevalent sign of this relationship is the gigantic kasa that Ace gave to him. For Ace's kindness, Oars Jr. is determined to save Ace.
As a giant of immense size, Oars Jr. has incredible strength. However, in contrast to Oars he is seen using a sword. Oars Jr. has a high amount a stamina, taking damage from three Shichibukai (one of whom sliced off his right leg), incoming marines, their Giants Squad and the marines' artillery without losing his resolve to save Ace. However, his large size was also apparently his own weakness, as he was so big it made him an easy target.

(Source: One Piece Wikia)