they/ah/erray/ee/oo/essay (That's roughly how the Spanish pronounce the letters in the name, which, being a name, stays the same, though it could conceivably be hispanified into 'dario').
It is a non-Spanish name, so it is the same in Spanish.
Darrell Royal's birth name is Darrell K. Royal.
Darrell Ware's birth name is Darrell Pascal Ware.
Darrell Weaver's birth name is Darrell Scott Weaver.
Dimebag Darrell's birth name is Darrell Lance Abbott.
Katrina Darrell's birth name is Katrina Chere Darrell.
Darrell Dess's birth name is Darrell Charles Dess.
Darrell Evers's birth name is Darrell Kenyatta Evers.
Darrell Evans's birth name is Darrell Wayne Evans.
Darrell Fancourt's birth name is Darrell David Leverson.
Darrell Calker's birth name is Darrell W. Calker.
Darrell Hammond's birth name is Darrell C. Hammond.