John Fitzalan born in 1223. He was Lord Oswestry, Clun, and Arundel and an English nobleman. He is sometimes counted as 6th Earl of Arundel although he was never called earl during his lifetime.

He married Maud le Boteler, daughter of Theobald le Botiller (Boteler) and Rohese (or Rohesia) de Verdun.

After his father's death in 1240 the Shropshire lordships of Oswestry and Clun were in the custody of John Lestrange, sheriff of Shropshire and member of a family long friendly with the Fitzalans, until John Fitzalan came of age in 1244. After the death of Hugh d'Aubigny in 1243 a quarter of Hugh's possessions, including the castle and manor of Arundel, were awarded to Fitzalan in the right of his mother. After he offered a relief of £1000 in May 1244 he took possession of Arundel and the family lands in Shropshire, including the castles at Clun, Oswestry, and Shrawardine.

John  Fitzalan was a significant figure in both national politics and those of the Welsh marches. Henry III granted him permission in July 1253 to pledge his lands for 500 marks to cover costs of accompanying the king in Gascony. In 1255 and 1256 Fulk (IV) Fitzwarine, lord of Whittington (just north of Oswestry), complained of attacks by Fitzalan's men. In August 1258 his men from Clun attacked Bishops Castle (Lydbury North), a large Shropshire manor belonging to the bishops of Hereford. His military power was so important that in August 1257 he was appointed captain for the custody of the march north of Montgomery, and in March 1258 was ordered to lead his men to Chester to participate in an expedition against Llywelyn ap Gruffudd. In 1259 he was one of eight royal negotiators sent to Montgomery Ford to settle breaches of the truce with Llywelyn. The latter complained in 1262 about raids on Bromfield by Fitzalan, Roger (III) de Mortimer, and John Lestrange.

The marcher barons were a major focus of opposition to Henry III and Fitzalan adhered to this party from late 1258. By June 1263 he and his son John were both active supporters of Simon de Montfort and in that month a group including Fitzalan, Roger Clifford, Humphrey (V) de Bohun, and Hamo L'Estrange attacked and captured the Poitevin royalist Bishop of Hereford, Peter d'Aigueblanche. On 12th July Fitzalan seized Bishops Castle, which the family refused to surrender for over six years. By late autumn the Lord Edward had won Fitzalan over to the royal side; on 24th December he was appointed as one of five keepers of the peace for Shropshire and Staffordshire, figures whose task it was to wrest administrative control of these counties from the baronially controlled sheriff. In January 1264 he was the eighth baron who swore to adhere to the agreement under which the king of France would arbitrate between Henry III and his barons. After being besieged with Earl Warenne in Rochester Castle, Fitzalan fought in the royal army and was captured at the battle of Lewes on 14th May. In April 1265 Montfort's government suspected his loyalty and ordered him to surrender either his son or Arundel Castle. After Montfort's defeat, Fitzalan was appointed on 18th April 1266 as keeper and defender of Sussex to help the sheriff arrest disturbers of the peace. In January 1267 he was ordered to investigate and quell treasonous plots in Sussex. He died c.12th November 1267, having ordered his body to be buried in Haughmond Abbey, Shropshire; his second wife outlived him. At death John was a very wealthy man.

John and Maude had a son:

John Fitzalan, 7th Earl of Arundel

Although Rishanger called John Fitzalan Earl of Arundel in 1264 and some modern scholars have occasionally followed this style, he did not apparently use this title. In 1258 he was called lord of Arundel and in 1266 John Fitzalan de Arundel.