I've mentioned before that it took Star Trek: The Next Generation a while to find its stride, and nowhere is that more evident than in the character of Lt. Worf. I thought the inclusion of a Klingon bridge officer was one of the more daring and creative efforts by the creators, who were otherwise plotting a fairly middle-of-the-fairway course with the new series. Data was a rejiggered Spock, for instance, while Riker gave us Kirk's swagger, and Dr. Crusher reprised McCoy's only-I-can-say-this-to-the-captain role while replacing the old boys' advice club with mild romantic tension. Troi was a soft 90's cheesecake bit that never worked for me, and even though the creators tried to avoid a Scotty redux with a miracle working chief engineer, eventually they returned to their roots and morphed Geordi LaForge into that role.
But Worf...initially I found him a disappointment. He was visually striking, Michael Dorn's carriage and delivery were zeroing in on the character, but they simply didn't give him enough to do other than snarl and glower. I think the problem was Yar, a character saved from being the least useful on the show by the chokingly awful presence of little Mary Sue Wesley Crusher. Yar crowded out Worf from his true calling as chief of security, and when she was blessedly tossed aside by the tar baby Armas, the way was cleared for Worf to shine. He grew, literally and figuratively, into the role, dominating the back mezzanine of the bridge with his physical presence and ruthless competence. The series began to really hit on all cylinders as it explored his background through the lens of the uneasy peace between the Federation and the Klingon Empire. Worf's relationships with Picard, with Riker, even the strange dalliance with Troi, allowed the character to expand and deepen. We learned about his nobility, his churning sense of personal and familial shame and inadequacy, and his simmering desire to prove himself. His quest for redemption, for himself and his people, provided great pathos to a series that was badly in need of it.
I haven't explored the later episodes of DS9, when I'm told his narrative continued to deliver some of latter-day Trek's better moments. It's not hard to believe. It took him some time to find himself, but Worf is one of the best things to come out of Star Trek since the original series.