Kam Solusar is a human Jedi Knight of the pre-Empire Order who survived the Purge, fell to the dark side under Imperial pressure, and was recovered by Luke Skywalker. He first appears in Kevin J. Anderson's Dark Apprentice (Bantam, 1994), the second Jedi Academy novel, and recurs across the Dark Horse comics of the same period.
His usefulness to the Legends continuity is structural. Luke's praxeum on Yavin 4 has a serious credibility problem — a man who trained for perhaps six weeks with two teachers, both dead, is now running a school — and Kam is the fix. He is an actual product of the old Order, and once he is stable he takes over most of the day-to-day instruction, which is why later novels can plausibly show competent Jedi coming out of Yavin.
He marries the historian Tionne, and the two of them become the Order's institutional memory and its teaching staff: she recovers what the Jedi used to know, he teaches people to use it. In the Yuuzhan Vong war and after, they run the academy on Ossus.
He is Legends, and he is one of the quiet reasons that continuity's version of the New Jedi Order feels like an institution rather than a hobby.
