Final answer:
The Undertale character starting with 'T' that is often loved by fans is Toriel. She is a motherly figure in the game and is known for her caring nature.
Step-by-step explanation:
The Undertale character that starts with 'T' and is often regarded as one of the best by fans is A. Toriel. She is a motherly figure that takes care of the protagonist early in the game and is known for her caring nature and offers of guidance and support. The answer does not include B. Temmie which is another character in the game that has its own charm, but is not typically considered the best character. C. Torbjorn is not an Undertale character and D. Toby Fox is the creator of Undertale and not a character within the game. When discussing who the 'best' character is, it can be subjective, but Toriel is a beloved character for her role in the game's narrative.