I agree that only our imagination is the limit when discussing potential life. If matter that is not completely frozen (ie atoms stop moving) will eventually organize into some self-replication, any energy source could be enough.

It could be on the surface on active star, neutron star (someone already tackled that in sci-fi), all kinds of dwarfs, nebulas, maybe even something living off dark energy? Or black hole.

Energy means movement, and if matter/energy will eventually arrange into something 'alive', it might be enough.