The giant, single-celled organism $Stentor\; coeruleus$ has a long history as a model system for studying pattern formation and regeneration in single cells. $Stentor\; coeruleus$ [1, 2] is a heterotrichous ciliate distantly related to familiar ciliate models, such as Tetrahymena or Paramecium. The primary distinguishing feature of $Stentor$ is its incredible size: a single cell is 1 mm long. Early developmental biologists, including T.H. Morgan [3], were attracted to the system because of its regenerative abilities-if large portions of a cell are surgically removed, the remnant reorganizes into a normal-looking but smaller cell with correct proportionality [2, 3]. These biologists were also drawn to $Stentor$ because it exhibits a rich repertoire of behaviors, including light avoidance, mechanosensitive contraction, food selection, and even the ability to habituate to touch, a simple form of learning usually seen in higher organisms [4]. While early microsurgical approaches demonstrated a startling array of regenerative and morphogenetic processes in this single-celled organism, $Stentor$ was never developed as a molecular model system. We report the sequencing of the $Stentor\; coeruleus$ macronuclear genome and reveal key features of the genome. First, we find that $Stentor$ uses the standard genetic code, suggesting that ciliate-specific genetic codes arose after $Stentor$ branched from other ciliates. We also discover that ploidy correlates with $Stentor$'s cell size. Finally, in the $Stentor$ genome, we discover the smallest spliceosomal introns reported for any species. The sequenced genome opens the door to molecular analysis of single-cell regeneration in $Stentor$.