Well, indeed, it depends on how you define hot!
Hot:
4. a typically high quantity regarding temperature
For this definition, I'm hoping David Tennant doesn't surpass the healthy norm of about 37°!
5. expressing or feeling intense emotion, such as embarrassment, anger, or lust
Respectably, David Tennant reveals little about his personal life and emotions to the general public. Thus, I'm not entirely sure how "hot" he is in this sense, but again we can hope not too much!
7. recent; fresh; new
David Tennant is about 41 years passed being regarded as this definition of hot!
9. much favoured or approved: a hot tip ; a hot favourite
According to
link , the Internet is "absolutely positive about David Tennant!" Over 2k hits support that the Internet is 98.3% positive regarding David Tennant.
13. informal sexually attractive
This is an incredibly subjective concept! What someone finds sexually attractive depends on his or her background, sexuality, and personal "kinks". I'm personally asexual, but regarding a most typical societal understanding of what is "sexy", I consider David Tennant to be high-ranked! Definitely up there in the 8-10/10 range.
18. slang impressive or good of its kind (esp in the phrase not so hot )
Again, the Internet LOVES David Tennant, and the Internet essentially is our media now-a-days!