For the letter K, I've decided to do Korah, who with two other Israelite men, started a rebellion in the book of Numbers. This happened while the Israelites were doing their 40 years of wandering in the desert.
Korah was a Levite. He would have had high duties for the Lord at the Tabernacle but it appears that he desired to be more than that. So he challenged Moses' leadership. He was joined by Dathan and Abiram and 250 other men. They come to Moses, saying that "the whole community is holy" and therefore, Moses should not be able to set himself higher than any other Israelite.
Moses replies that God will chose who is holy and tells the rebels to bring censers of incense tomorrow so that God can chose. He goes on further to tell Korah that it should be enough that God has already set him apart as a Levite for important work at the tabernacle.
Dathan and Abiram (who are from the tribe of Reuben) make the excuse that Moses has not brought them to the Promised Land and that they were better off in Egypt. This theme is used a lot throughout the wandering in the desert. The people of Israel often made their hard years of slavery in Egypt sound rosy.
So, the showdown begins. God tells Moses and Aaron to step away from the other 250 men plus Korah, Dathan and Abiram. God then causes the earth to swallow Korah and his two compatriots along with their households and possessions. Then God sends fire and takes out the other 250 men.
The bronze censers of the 250 men are turned into an overlay for the altar because they are holy and to serve as a reminder to the Israelites of the events.
You would think that the Israelites would have been "seized with a great fear" or something but instead they turn the blame on Moses and Aaron saying "you have killed the LORD's people."
God strikes the Israelites down with a plague until Aaron quickly offers a sacrifice of atonement for their sin but 14,700 people die as a result.
It never ceases to amaze me the things that the children of Israel did despite having God's continued presence (remember, the pillar of cloud and pillar of fire were always there and they had seen God's wonders at Mount Sinai). Perhaps this is why Jesus said "Blessed are they who have not seen and yet have believed."