Dannelly was born in Würzburg, Germany then moved with his family to Baltimore, Maryland at age 11.

[5] Dannelly graduated from the University of Maryland, Baltimore County with a degree in visual arts in 1997.

[7] He and Urban began writing the script while attending the American Film Institute Conservatory.

[1] He was set to direct a film based on The Guided Man by L. Sprague de Camp, but the project was shelved.

[1] In 2017, Dannelly worked as a director on two episodes of the second season of the Netflix series Haters Back Off, starring Colleen Ballinger (Miranda Sings), Angela Kinsey and Erik Stocklin.