Linwood Vrooman Carter (June 9, 1930 – February 7, 1988) was an American author of science fiction and fantasy, as well as an editor and critic. He usually wrote as Lin Carter; known pseudonyms include H. P. Lowcraft (for an H. P. Lovecraft parody) and Grail Undwin.

He was born in St. Petersburg, Florida. He was an avid reader of science fiction and fantasy in his youth and became broadly knowledgeable in the field. He was also quite active in fandom.

Carter served in the United States Army (Infantry, Korea, 1951–53), after which he attended Columbia University (1953–54). He was a copywriter for some years before writing full-time. He married twice, first to Judith Ellen Hershkovitz (married 1959, divorced 1960) and later to Noel Vreeland (married 1963, while they both worked for Prentice-Hall publishers; divorced 1975). He was an advertising and publishers copywriter (1957–69). From 1969 he was a freelance writer and editorial consultant. During much of his writing career he lived in Hollis, New York.