The evolution of Oscar the Grouch.

Image As seen in / Year Notes
Sesame Street
Season 1
The original Oscar puppet is orange. This version used in the early episodes of season 1 is built around a right-handed work glove, with no foam interior. At this time, the way the set is built forces performer Caroll Spinney to use his left hand, making this version of the puppet look awkward. This puppet's eyes can shift left to right.
Sesame Street
Season 1
Oscar is refurbished for episodes 9 and 10 with an arm (he had no limbs before).
Sesame Street
Season 1
This rebuilt Oscar, used for the remainder of season 1, has a larger foam head and an eyebrow mechanism. The set was changed to allow Spinney to work with his right hand.
The Flip Wilson Show
Episode #5
Between the first and second seasons of Sesame Street, Oscar appeared on The Flip Wilson Show with a new design including green fur and a blue eyebrow. His head had yet to take its final shape. Shortly after, in the second season premiere (Episode 0131) an altered version of this puppet would be used as Granny Grouch.

Sesame Street
(late 1970-1986)
For the second season, Oscar's eyebrow has reverted back to brown and his head has been remodeled into its final shape. Although the puppet has been refurbished since the 70s, the design has stayed consistent. In The Wisdom of Big Bird, Spinney says that the current Oscar's eyebrow is still the same piece of fur used for the original orange Oscar puppet.

Sesame Street
Episode 0573
(ca. early - mid 1970s)
This rarely seen Oscar variant has smaller eyes and a rounder mouth than the one regularly used. Another defining feature is that not only is his eyebrow mobile, but his eyes are as well (like the original puppet). This particular Oscar puppet can also be spotted during "C is for Cookie," as well as the cover of a 45rpm single, and was later reused as Oscar's grandpa.

Sesame Street
Oscar's fur becomes matted over time, which makes it appear shorter and less messy. His eyes are also slightly farther apart.
Sesame Street
Season 44
Oscar is refurbished with darker green fur and a solid pink tongue.
Sesame Street
Season 46
Another Oscar puppet that had been used for live appearances is used as an alternate beginning with season 46. This puppet has shaggier fur, bushier eyebrows and a crooked jaw, giving him a visible chin.
Design sketches for Sesame Street
Jim Henson had initially intended Oscar to be magenta, as opposed to orange. The reason for the color change was because at the time, television cameras couldn’t process magenta shades well. In these early sketches, Henson experimented with how the puppet would move, appearing slyer and more sinister than the grouch he would become.