Torus knot groups are certainly linear. The universal cover of a torus knot complement is Euclidean space, and the action of the group on this cover factors through "translations on euclidean space" cross $PSL_2(\mathbb R)$. Both linear groups.
Generally it's conjectured that all 3-manifold groups are linear. For all I know, there might be a proof already. See What is known about a 3-manifold $M$ when its fundamental group is linear?