Coached one of state’s most dominant cross country and track and field programs spanning five decades, winning 38 state titles from 1976 to 2015 (17 boys cross country titles; 6 girls’ cross country titles; 9 boys’ track titles and 7 girls’ track titles), and 65 conference titles (17 in boys’ cross country; 6 in girls’ cross country; 24 in boys’ track and field and 18 in girls’ track and field). In one unprecedented stretch, his boys’ cross country teams won 13 straight state titles (1983-1995).  

As head cross country and track coach at Durham Academy, he had 10 boys and 7 girls win individual state cross country titles, and 82 boys’ and 104 girls’ win state titles in track and field. 

The Durham City-County Cross Country Championship also named an award after him, the “Dennis M. Cullen Trophy,” given each year to the best combined boys’ and girls’ program at the Durham City-County meet.  

Cullen has also been a key organizer for Durham County Special Olympics for 35 years, and was given Durham Academy’s prestigious F. Robertson Hershey Distinguished Faculty Award. 

He is a member of the North Carolina Independent Schools Athletic Association Hall of Fame and the Durham Academy Hall of Fame.