A desk lamp sits on a desk. A ball rolls into frame. The lamp is sentient and animate, and it has a child, in the person of another, smaller desk lamp. Luxo Sr. and its child Luxo Jr. kick the ball around a while. Luxo Jr. then jumps on the ball and starts bouncing on it—with unfortunate consequences.
Luxo Jr. was made by Pixar when it was a computer software company, and the purpose of the short was to demonstrate the utility of computers in creating animated films. The huge success of this short and Lasseter's follow-up Tin Toy led to Pixar abandoning the computer software business and becoming a wildly successful animation studio.
Luxo Jr., the character, became the symbol/mascot of Pixar, and has appeared in the credits of every animated film Pixar has made since.
- Ambiguous Gender: Luxo Sr. and Jr., who as sentient lamps, don't really have visible gender indicators. John Lasseter considered it a personal accomplishment when a colleague of his at SIGGRAPH, who usually asks him technical questions about his work, was instead pleading to know whether Luxo Sr. was the mother or the father.
- Animate Inanimate Object: Luxo Sr., and Luxo Jr., but not the ball (luckily for the ball).
- Aside Glance: Luxo Sr. shoots one at the camera and then shakes its head. (Luxo Jr. does this in all the later Pixar title cards.)
- Character Title: Luxo Jr refers to the smaller lamp.
- Creative Closing Credits: The closing credits show various sketches and drawings that were part of the making of the film.
- Easter Egg: The Luxo ball from this short has made it into many other Pixar films.
- Happy Ending: Luxo Jr. gets a second, bigger ball to play with.
- No Flow in CGI: This early CGI short managed to sidestep this problem by having objects with smooth, non-flowing surfaces—except for the power cords to the lamps. That proved the most difficult thing to animate.
- Vanity Plate: The Pixar vanity plate of the lamp hopping up and down on the 'i' until it collapses, and then replacing it, came from this short.