The title character of an unfinished poem by this man encounters Geraldine,
The title character of an unfinished poem by this man encounters Geraldine, who claims to have been abducted.  Another poem by this man ends with an image of "silent icicles / quietly shining to the quiet moon," and describes how the titular phenomenon "performs its secret ministry." In addition to "Frost at Midnight," this author wrote a poem which features a "damsel with a dulcimer" and earlier describes the River Alph running down to a sunless sea.  The title emperor of that poem lives in Xanadu and decrees a "stately pleasure dome." For 10 points, name this poet of "Kubla Khan" who also wrote about the slaying of an albatross in The Rime of the Ancient Mariner.
The title character of an unfinished poem by this man encounters Geraldine, who claims to have been abducted.  
Samuel Taylor Coleridge