Lego teased a new Donkey Kong character figure during its Mario Day livestream. Not much is known about it--other than Donkey Kong having space for another Lego character to ride on his back--and more info, like pricing, will likely be available closer to summer.
Just from the teaser image, it looks like the Donkey Kong figure is similar in size to the electronic Mario figure (the one available in the Mario Starter Course kit).
In addition to Donkey Kong, Dry Bowser and his castle expansion was also announced by Lego. Dry Bowser's kit ($110) will be available on August 1, and preorders are not available yet. Dry Bowser's Castle Expansion kit features a little gym area and five Lego characters including a Dry Bowser, a Magmaargh, a Bone Piranha Plant, a Bone Goomba, and a Purple Toad.