Animated scarecrow (The Night Walkers)
Following the Doctor's exile on Earth, the Time Lords had not yet carried out his forced regeneration. To do so, they animated scarecrows in order to carry out that portion of his sentence.
Overview
The Second Doctor lived on Earth at this time in the Carlton Grange Hotel, and generally enjoyed a relatively luxurious life of considerable fame.
One night, while appearing on the game show, Explain My Mystery, the Doctor was asked to consider the case of Mr Glenlock-Hogan, a farmer with the walking scarecrows. He wasn't able to do so. He arranged for an off-camera visit to the farm. When he arrived, the scarecrows duly began to walk around. Eventually, they captured him and revealed that they had been animated by the Time Lords in order to carry out the remaining part of his sentence. Inside the TARDIS, they forced him to regenerate and, while he was doing so, set the TARDIS to dematerialise, and quickly left, thus setting up the opening moments of his next incarnation's existence. (TVC: The Night Walkers)