Professor Tofty is an elderly wizard who administers OWLs in Defense Against the Dark Arts, Astronomy, and History of Magic. During Harry's Defense OWL, Professor Tofty asks him to produce a Patronus for extra credit, whispering, "I heard, from my dear friend Tiberius Ogden, that you can produce a Patronus? For a bonus point ...?" (31.98). He admires Harry's efforts immensely.
In addition to his enthusiasm, Professor Tofty also gives the impression of being a kindly man: when he spots Professor McGonagall being stunned by Aurors at Hagrid's cottage, he forgets all about the Astronomy exam he's supposed to be overseeing and shouts that her attackers are all cowards. Later, when Harry appears to be having a seizure during his History of Magic OWL (in fact, he's seeing a vision of Voldemort), Professor Tofty tells him gently, "Pressure of examinations! [...] It happens, young man, it happens!" (32.4). He seems like a genuinely sweet old man, the kind of guy you would want to have giving you an exam.