Well it depends on what you think is sad... If he died in front of his companion although the companion did not know he would regenerate and you think that that is sad, then yes that is sad.
robot
According to an interview with Doctor Who Magazine, Tom Baker lives a solitary life with his wife in the countryside and enjoys going on long walks with his dog, Poppy.
Tom Nook is never sad,but he does blurt out secrets.He talks about his love,Sable when he tells you his secret.
Tom Nook has many stories to why he is sad. When you ask him, you can get the whole story from him. It is different each time he is depressed.
The only actor to play two forms of the Doctor in the 12 count regeneration cycle was David Tennant. Matt Smith who played the Doctor after Tennant even made a joke about how much vanity the previous doctor version had and had to repeat himself in his next regeneration. HOWEVER, no actor who has quit playing the Doctor has returned to play the role again. But with that being said, Tom Baker, who played the role of the 4th Doctor, did make an appearance on "The Day of the Doctor" and told Matt Smith's version of the Doctor that he might or might not be a future version of the Doctor "trying on familiar faces".
Tom Nook has many stories to why he is sad. When you ask him, you can get the whole story from him. It is different each time he is depressed.
Tom Baker
Occasionally, he acts sad because of his work. Talk to him for more information.
Tom doesnt believe in love, he believes in lust. Sad, but true :[
The Fourth Doctor, played by Tom Baker, had K9 as his companion. K9 is a robotic dog created by the Fourth Doctor in the TV series "Doctor Who".
It was Tom Baker; he played the Doctor for seven years.
Tom Baker, 1974-81