Loki

"Whos is that?" called a voice from inside the case, and an elderly giantess came out. There was comething vaguely familiar about her, but none of the messengers was entirely certain what it was. "I am Thokk," she said, which means "gratitude". "Why are you here?"
"We have asked each thing there is if it would weep for Balder, who is dead. Beautiful Balder, killed by his blind brother. For each of us misses Balder as we would miss the sun in the sky, were it never to shine again. And each of us weeps for him."
The giantess scratched her nose, cleared her throat and spat on to the rock.
"Old Thokk won't weep for Balder," she said bluntly. "Alive or dead, old Odin's son brought me nothing but misery and aggravation. I'm glad he's gone, Good riddance to bad rubbish. Let Hel keep him."
Then she shuffled back into the darkness of her cave and was lost to sight.

[...]

And by then they had also realised who old Thokk reminded them of: she had moved and talked much like Loki, the son of Laufey.
"I expect it was really Loki in disguise," said Thor. "Of course it was Loki, It's always Loki."