Mr. and Mrs. Thistlewhite are the parents of Ignatius Thistlewhite in the Rankin/Bass special The Year Without a Santa Claus. Not seen in the original poem the special is based on, they live in Southtown with their son and his pet dog.
The two are first seen when Iggy meets a thinly-disguised Santa Claus (going under the name "Mr. Klaus"). They invite their son's new friend into their home to cure his sickness with Mrs. Thistlewhite's home blend of tea. During this, Mr. Thistlewhite recalls the moment in his childhood when he truly believed in Santa Claus when Iggy asks him about it, and expresses this sentiment in the song "I Believe in Santa Claus." After the family figures out the identity of their visitor when he goes to pay for Vixen's bail at the dog pound, Mr. Thistlewhite urges his son to help Santa in any way he can, suggesting he talk to the mayor about it. Iggy's parents are not seen again until the very end of the special, when Iggy gives them Christmas presents on Christmas morning.
Mrs. Thistlewhite makes a cameo appearance at the end of Rudolph's Shiny New Year, oddly without her husband or her son; she can be seen among the people celebrating the arrival of the new year at Father Time's castle.
In the 2006 live-action remake, Mr. Thistlewhite and the Mayor of Southtown are merged into a single composite character, the ambitious Mayor Thistlewhite, while Mrs. Thistlewhite is given the first name Rachel.