Focko Ukena (Neermoor, 1360 or 1370 – 1435) was an East Frisian chieftain (hovetling) who played an important part in the struggle between the Vetkopers and Schieringers in the provinces of Groningen and Friesland. Aside from this he was one of the leading figures in the resistance against the forts of stately authority in East-Frisia of the tom Brok family.
In the north of present-day Netherlands, roughly the current provinces of Groningen and Friesland, there existed virtually no state authority. This freedom was threatened from several sides.
In what is now East Frisia, the family of tom Brok was attempting to establish a dynasty. And in what is now the province of Friesland, the counts of Holland were expanding their influence. The city of Groningen was also trying to expand its power. And through all of this the rivalry of the Vetkopers and Schieringers played.
Ukena was originally a military commander under Keno tom Brok. As such he defeated Sicka Sjaerda at Noordhorn in 1417, and conquered Dokkum in 1418. After the reconquest of Dokkum by the Schieringers, he disembarked at Hindeloopen and defeated the Schieringers at the Palesloot.
He took Stavoren and besieged Sloten, but was forced to withdraw by the troops of John III, Duke of Bavaria, Count of Holland. Ukena was the first to sign the Peace of Groningen on 1 February 1422, which was aimed against all foreign lords. Next he battled with the Hansa against the Likedelers, and expelled them from Ezumazijl and Dokkum. Afterwards he turned against tom Brok and was primarily active in East Frisia.