This is one of the hardest ab exercises to perform. The ab gains are decent, but the gains in balance and proprioceptive control can be staunch.

This exercise will build your balance and core stability more than your ab muscles. This can be good for functional fitness but not ideal for a chiseled 6-pack.

The GHD sit-up is often used in CrossFit training. Physique athletes should also take advantage of this exercise because it can really help build great abs.

Seated leg raises while holding weight can really challenge you pending how much weight you hold and how well you execute the movement.

This exercise can be used by beginner lifters as a finisher to an ab routine, a progressive exercise to build strength to soon attempt more difficult exercises, and/or a core stability developer.

This is one of the most common ab finishers. Perfect this movement, then try to do it with your torso off the ground.

This is one of the most growth-promoting floor exercises for the core making it a fabulous finisher to an ab routine.

Maintaining a static V-Hold position is difficult. To make it even more challenging, yet rewarding, add some side-to-side scissor kicks!

Scissor kicks, also called flutter kicks, are one of the most popular exercises. The side-to-side variant is a good tool to add to your arsenal if you're seeking an ab finisher on the floor.

Weighted planks, like planks, are still best suited for older adults and beginners looking to develop foundational core strength.

The plank can be a good exercise for older adults and beginners looking to develop core and postural strength.

Mountain climbers are best suited as a calorie burning finisher rather than an ab developer.

This exercise is great as the step in the progression towards performing hanging leg raises (legs straight, holding weight) which is the alpha in terms of gains-inducing ab exercises. 

The hanging leg raises with the knees bent can be used to progress in strength to work up towards using the legs straight variations or as dropsets after reaching failure with your legs straight.

This is the GOAT of ab building exercises and receives our highest grade for 8-pack potential.

Yet another great finisher to potentially add to your arsenal.