Walter lord of Boissy-sans-Avoir, also known as Walter the Penniless (died 1096) was a Frankish crusader knight who was the Lord of Sans-Avoir, and participated in the First Crusade, where he was killed.


Walter Sans-Avoir was born in France in Boissy-sans-Avoir, becoming the Duke of Sans-Avoir. On April 15, 1096, he joined the First Crusade after Peter the Hermit's preaching tours in Cologne, and he brought an army with 8 knights leading a primarily-French army from the Ille-de-France, through the Kingdom of Hungary, and to the Byzantine Empire's strongholds in Asia Minor. 

Walter Sans-Avoir was killed in the Battle of Kibotos, when the Turks around Nicaea attacked him in a fast-paced action which left him pierced by seven arrows, and Reynald of Broyes also fell.