Humphrey de Bohun, 4th Earl of Hereford (1276 – March 16, 1322) was a member of an important Norman family of the Welsh Marches. His father was Humphrey de Bohun, 3rd Earl of Hereford and his mother was Maud de Fiennes, daughter of Enguerrand II de Fiennes. He was born at Pleshey Castle located in Essex, England. The castle is nothing more than an earthwork ruin now.

He succeeded his father as Earl of Hereford and Earl of Essex, and Lord High Constable. Humphrey held the title of "Bearer of the Swan Badge". He married Elizabeth of Rhuddlan, daughter of King Edward I of England and his first Queen consort Eleanor of Castile, on November 14, 1302, at Westminster. She gave him 10 children:
1. Margaret de Bohun (September 1303 – 1305)
2. Eleanor de Bohun (October 1304), married James Butler, 1st Earl of Ormonde and Thomas Dagworth, 1st Baron Dagworth.
3. Humphrey de Bohun (1305 – died young)
4. John de Bohun, 5th Earl of Hereford (November 23, 1306 – 1335)
5. Humphrey de Bohun, 6th Earl of Hereford (December 6, 1309 – 1361)
6. Margaret de Bohun (April 3, 1311 – 1391), married Hugh Courtenay, 2nd Earl of Devon
7. William de Bohun, 1st Earl of Northampton (1312–1360). Twin of Edward.
8. Edward de Bohun (1312–1334). Twin of William.
9. Eneas de Bohun, died after 1322, when he's mentioned in his father's will.
10. Isabel de Bohun (b. May 5, 1316). Elizabeth died in childbirth, and this child died a few days afterwards.

At the Battle of Bannockburn, he charged alone at Robert the Bruce, only to be felled by the Bruce and held for ransom by his wife. In this battle, his kinsman Henry de Bohun was also killed by Bruce. Humphrey was killed while fighting Andrew de Harclay, at the Battle of Boroughbridge in a particularly gory manner. As recounted in The Greatest Traitor by Ian Mortimer, page 124:

"[The 4th Earl of] Hereford led the fight on the bridge, but he and his men were caught in the arrow fire. Then one of de Harclay's pikemen, concealed beneath the bridge, thrust upwards between the planks and skewered the Earl of Hereford through the anus, twisting the head of the iron pike into his intestines. His dying screams turned the advance into a panic."