Arisia is a Boston-area, volunteer run science fiction convention, named for a planet in the Lensman novels by E. E. "Doc" Smith. The name was chosen as an homage to an older Boston-area con, Boskone, which took the typical ending for a convention—con—and then altered the spelling to match the name of an organization in the Lensmen books.

Arisia was first held in 1990, and its attendance has grown from 842 to over 3200. Arisias 2007–2010 were held at the Hyatt Regency in Cambridge, MA. Arisia 2011 and 2012 were at the Westin Boston Waterfront in Boston, MA, as will be the next convention, scheduled for January 18–21, 2013.

Regular events include one of the largest Masquerades (costume contests) on the East Coast; "Fast Track" programming for children; a demonstration of historical fighting techniques; gaming; and film, video, and anime rooms. Other events that have been recently included are a blood drive, a drumming circle, Friday and Saturday evening dances, and live radio dramas.

The Arisia Corporation is the body that funds and promotes the annual Arisia convention; additional activities include awarding grants to other related organizations. Membership costs $24 per year starting in September, pro-rated for members who join during later months. Corporate positions are elected by the voting body (defined as members who have attended one previous corporate meeting) in September. Meetings are held monthly, usually at MIT, and are open to the public.