Muiredach's High Cross, Celtic high cross at Monasterboice, Ireland

Muiredach's High Cross is a sandstone monument at Monasterboice carved with detailed relief work across all four sides. The carvings depict over a hundred human figures arranged in scenes telling biblical and religious stories.

The cross is dated to about 900–920 CE, though a 9th-century origin has also been proposed. An inscription on the west face's base reads ÓR DO MUIREDACH LAS NDERNAD IN CHROS, "a prayer for Muiredach who had this cross made"; this is likely Muiredach mac Domhnall, abbot of Monasterboice and abbot-elect of Armagh, who died in 923. Two other Muiredachs have been suggested: an abbot who died in 844 and Muiredach mac Cathail, a king who died in 867.

The name comes from an Irish inscription on the west face: ÓR DO MUIREDACH LAS NDERNAD IN CHROS, "a prayer for Muiredach who had this cross made". The Muiredach named is probably abbot Muiredach mac Domhnall, who died in 923. High crosses also marked the sanctuary around a church and served as focal points for markets that grew up at monastic sites.

The cross stands freely accessible year-round on the monastery grounds in County Louth with no entrance fee required. Visitors can examine the fine carvings closely, though it is worth noting that weathering has softened some of the stone details over time.

Archaeologist Robert Alexander Stewart Macalister counted 124 figures carved on the cross, 119 of them in costume. All but one are bare-headed; the single figure wearing headgear is Goliath, shown in a conical helmet. Only Adam, Cain, Moses and Saul are given beards.