For a (pseudo-)Riemannian manifold a Killing tensor is a section of a symmetric power of the tangent bundle
which is covariantly constant in that
\nabla_{(\mu K_{\alpha_1, \cdots, \alpha_k}) = 0
\,.
For this reduces to the notion of Killing vector.
For every Killing tensor on the dynamics of the relativistic particle on has a further conserved quantity. In the canonical case this quantity is the energy Hamiltonian of the particle.
The analog of this for spinning particles and superparticles are Killing-Yano tensors.