The name Macsen is a boy's name of Welsh origin meaning "greatest". Macsen and discussed in our forums with posts like "Rate the Previous Signature!".
From the experts:
Macsen may sound like a modern invention, cousin to Jackson and Maxon, but it's a longtime Welsh variation of Maximus with evocative roots in legend. Macsen Wledig is another name for the Roman emperor Magnus Maximus, was played an important role in Welsh history and was further immortalized in a poem celebrating his dream about his lover Elen. Macsen also appears in Arthurian legend.