|William 'the Lion' succeeded his brother: married 5 September 1186 at Woodstock, Ermengarde, daughter of Richard, Vicecomes de Bellomonte: died at Stirling 4 December 1214, and was buried at Arbroath. By his wife, who died 11 February 1233-4 and was buried at Balmerino, he had:-
- 1. Alexander, afterwards king.
- 2. Margaret, was married, at York in 1221, to Hubert de Burgh, Justiciar of England and Ireland.
- 3. Isabella, was married to Roger Bigod, Earl of Norfolk, and died s.p.
- 4. Marjory, was married, at Berwick 1 August 1235, to Gilbert, Earl of Pembroke. She died s.p. 17 November 1244, and was buried in London.
King William had several illegitimate children:-
- 1. Robert de London.
- 2. Henry Galightly, whose son Patrick Galightly was a Competitor in 1291.
- 3. Isabella, whose mother was a daughter of Robert Avenel; married, first, in 1183, to Robert de Brus, and second, in 1191 to Robert de Ros. Her great-grandson William de Ros was a Competitor in 1291.
- 4. Ada, was married in 1184 to Patrick de Dunbar, fifth Earl of Dunbar; she died in 1200. Her great-grandson Patrick de Dunbar was a Competitor in 1291.
- 5. Margaret, whose mother was a daughter of Adam de Hythus, was married to Eustace de Vesci. Her grandson William de Vesci was a Competitor in 1291.
- 6. Aufrica, was married to William de Say. Her great-grandson Roger de Mandeville was a Competitor in 1291.