Yes you can use the comparative form:

He is the tallest person in my class.

No-one in my class is as tall as him

No-one in the class is taller than him / he is.

 

Although we usually use taller than him when speaking informally, the correct form is taller than he ( is tall).

It depends whether �than� is acting as a conjuncion or a preposition and this particular argument about English usage has been going on for years.

 

An explanation is given here:

Quote:

So remember, than he and than him are both defensible, but not all grammar mavens feel this way. Therefore, I would avoid the prepositional use in formal settings, such as a research paper or job interview�and I would argue, advertising, but Cadbury obviously feels otherwise. The usage note in The American Heritage Dictionary (4) agrees: �The writer who risks a sentence like Mary is taller than him in formal writing must be prepared to defend the usage against objections of critics.� Unfortunately, defending your grammar during an interview is not the best way to make a good impression.