Walter Bailloch, also known as Walter Bailloch Stewart (1225/1230 – 1293/1294), was distinguished by the sobriquet Bailloch or Balloch, a Gaelic nickname roughly translated as "the freckled". He was the Earl of Menteith jure uxoris.
Walter was a younger son of Walter Stewart, 3rd High Steward of Scotland, and his wife Beatrix of Angus, daughter of Gilchrist, Earl of Angus. In 1258-59, Walter accompanied Louis IV of France on his Crusade, according to tradition. After the death of King Alexander II of Scotland he was aligned with the "English faction", and in 1255 secured the persons of the young King and Queen, but he was not at this time allowed to a share in the government. About 1260, when Isabella, Countess of Menteith and her husband Walter Comyn, Lord of Badenoch were forced to leave Scotland, the magnates of Scotland arranged the marriage of her sister, Mary, to Walter Stewart, who took possession of the lands and title, with questions of legal ownership being reserved. He was certainly using the title of earl (jure uxoris) before 17 April 1261, when he was witness to a grant to the Paisley Abbey.
In the following year Dubhghall mac Suibhne granted to the earl the lands of Skipnish, Killislate, and others, being that part of Kintyre called South Knapdale and the parish of Kilcalmonell. Following on this, the Earl granted the church of Kilcalmonell at Clachan to the monks of Paisley. He also made grants to Kilwinning Abbey of churches in Knapdale, which show that he had possession of North Knapdale also. About 1263 the earl was Sheriff of Ayr, and aided in making preparations to repel the expected invasion of King Haakon IV of Norway. He and his brother Alexander Stewart, 4th High Steward of Scotland were joint commanders of the Scots in the Battle of Largs. The earl was Sheriff of Dumbarton in 1271 until 1288. On 25 July 1281 he was one of the witnesses to and guarantors of the marriage contract of the Princess Margaret with Eirik II of Norway. He, Countess Mary, and a party of Scots barons traveled to Norway accompanying the princess and her dowry of fourteen thousand marks. In 1285 he and his Countess were again attacked by the rival claimants William Comyn and his wife Isabella, their claim having been in 1282 pressed upon King Alexander III of Scotland by the English King, and in a Parliament at Scone it was decided that the earldom should be divided into two portions.