'Sentinel' Anti missile Missile

A small, space-to-space missile of the Hyperion Federation.
The Sentinel serves as a (relatively) cheap, highly maneuverable missile that is most commonly used as an anti missile missile, though it can serve other roles such as anti fighter.
The Sentinel also makes use of relatively large and highly powerful photon thrusters on all sides. This allows it to accelerate with huge forces which makes it much easier to engage fast targets that might often be changing trajectory a lot such as an enemy missile. Most of the missile volume is taken up by the powerful thrusters. 
It's most used warhead, fragmentation, creates a large number of dartlike fragments on detonation. These travel at an extremely high velocity due to their very small size and are able to penetrate into extremely light armour such as that of missiles. Due to the sheer volume of fragments involved, there could be hundreds of extremely small holes in all nearby targets. This causes extreme damage to all kinds of missiles and very likely result in their destruction. As the detonation one is quite large, it can still be devastating to a missile that it has missed. Although this is the most commonly used warhead, it can be fitted with different warheads, probably each used against different targets. Photon warheads, quark-gluon plasma warheads, as well as the more unethical antimatter and negentropy warheads, but there would be more.