I adore Otto.Ottilie (I would pronounce Ott-ah-lie) and Ottoline (I'd pronounce -line) seem kind of feminine to me. (Like Madeline) Other 'O' Names that caught my eye: Orrin Oakley Oliver Orsen Oscar Omar (Omario) Otis Ottavio (nn Otto) Otway (nn Otto) Ottney (prn. Ott-knee)