What 2 sports have a fun Variation called "Killer"

There may be others but I'm sticking to what I know

Sepak Tekraw is a possible answer.

Adding to my question Both versions are played for Money but when I've seen them played its just last man left is the winner (No Money)

Now, I notice you call them sports, Bedstor, and although I would have called them games, I see that Wikipedia includes the following in a list of pub 'sports':

Killer Darts:
To begin, an order of play is decided, and each player throws one dart 'bad-handed' (left-handed players throw right-handed and vice-versa) at the board to decide their number. Obviously, if a dart misses or hits a number that is already allocated, the player retries. Each player is allocated a set number of lives (usually 5) and is generally required to put a small stake into a pot. It is a good tactic to avoid being adjacent to somebody elses number.

Players start by taking turns to aim at their allocated number, scoring a life for each dart that hits it, 2 lives for a double and 3 lives for a treble. Once a player has scored 5 lives, that player is a 'killer' until somebody else deducts one or more lives from his score. However, a player must get EXACTLY 5 lives to become a killer, if he overshoots, then his score is deducted by the amount exceeded. For instance, if a player is on 4 lives and hits a treble of his number, the first of the 3 lives scored takes the player to 5 but the remaining 2 lives are deducted - so the end result is a score of 3 lives.

Once a player is a killer, they aim at any of the other player's numbers. Each time they do, the appropriate number of lives is deducted from the victimised player's score. When a player is reduced to below 0, that player is out of the game. For instance if a player has 1 life and a killer hits that player's number's double, that player's score is reduced to -1 and he is out of the game.

The final player left in the game is the winner and collects the pot. The rules of darts

Killer Pool:
Killer is a multi-player folk variant of straight pool in which each player is assigned a set number of "lives" and takes one shot per inning to attempt to pocket (pot) a ball, or else lose a life. Usually if the player scratches then an additional life is lost. It is a popular pub game because it can involve a potentially unlimited number of players, and offers the opportunity for each player to bet a small amount of money for a reasonable return in winner-takes-all. There are often other local subrules such as potting the black (8 ball), or any two balls in one shot, gives the player an extra life, or that failure to pocket a ball on the break shot does not cost a life (in which case the shooter shoots again). The game is sometimes called killer pool.
Wikipedia

Same links as Me dg

I've played both and got KO'd early
I used to be not bad at darts.Have played against County League Players(Who are 1 step shy of Professionals) and gone close