Loki

He rode northerly, and he followed the path down until he saw before him a huge high wall and the gates to Hel, which were higher than the tallest tree. Then he dismounted from his horse, and he tightened the girth strap. He remounted, and holding right to the saale, he urged Sleipnir faster and faster, and at the last it leapt, a jump like no horse has made before or since, and it cleared the gates of Hel and landed safely upon the other side, in Hel's domain, where no living person can ever go.