A Blast KO is a type of KO in the Super Smash Bros. series. It is the most common KO as it can happen on the side and bottom Blast lines in the first three games and on every blast line in Super Smash Bros. for Nintendo 3DS and Wii U.
The Blast KO appears in different colors. The color depends on the fighter his/herself. The colors of the blast are the same as the color indicators of the players. (Super Smash Bros., Super Smash Bros. Melee, Super Smash Bros. Brawl, and Super Smash Bros. for Nintendo 3DS/Wii U: 1st-Red, 2nd-Blue, 3rd-Yellow, 4th Green, : 5th-Orange, 6th-Cyan, 7th-Purple & 8th-Slate). As for CPUs (Computer Players) and FPs (Figure Players), the color indicator is grey for CPUs and rainbow colored for FPs, so their Blast KO is grey.
When playing in a team battle, the color of the Blast KO will match the team colors Red, Blue, or Green. (Yellow is introduced as a new team color in Super Smash Bros. for Wii U's 8 Player Smash.)