From Muppet Wiki

Dustin Hoffman (b. 1937) is an Academy Award-winning actor whose films include The Graduate, Midnight Cowboy, Marathon Man, Kramer vs. Kramer, Tootsie, Rain Man and Mr. Magorium's Wonder Emporium.

References

The 1999 calendar Muppet Movie Parodies: Our Wedding or Your Funeral featured a movie poster for The Undergraduate, a spoof in which Kermit played the Hoffman role of Benjamin Braddock, and Miss Piggy played the Anne Bancroft role of Mrs. Robinson.

Hoffman's role as Raymond Babbit in Rain Man was spoofed in Muppets Tonight episode 201, with the character Purple Rain Man.

Rizzo the Rat's name is also based on Hoffman's character from Midnight Cowboy, Ratso Rizzo.