Gandalf
Gandalf's transformative abilities are considerable. He can produce fire from his staff, illuminate caverns, and terrify Balrogs with dramatic pronouncements. His transformation from Grey to White following his resurrection demonstrated capacity for personal evolution on a cosmic scale. More significantly, his subtle influence has transformed ordinary Hobbits into world-saving heroes, a feat requiring approximately 80 years of patience with Bilbo alone. He transforms through inspiration, guidance, and the occasional application of magical fireworks that remain legendary in the Shire's collective memory.
Time
Time transforms absolutely everything without exception or effort. It converts hydrogen into helium in stellar cores, transforms solid rock into soil, and gradually ensures that all ordered systems eventually succumb to entropy. Time has transformed single-celled organisms into the extraordinary diversity of life on Earth over 3.8 billion years. It transforms youth into age, potential into memory, and future into past with mechanical inevitability. Where Gandalf must work to achieve transformation, time simply exists, and transformation occurs as a natural consequence of its passage.