Johnston is currently starring in the sitcom 'Leanne' alongside comedian Leanne Morgan Kristen Johnston's enduring love for her former 3rd Rock from the Sun costar John Lithgow is out of this world.

Johnston praises Lithgow for setting the example of "how to be on a set and how to be a graceful, cool person that everyone wants to work with" Speaking exclusively to PEOPLE, Johnston, 57, reveals ...