Preheat your grill to medium-high heat.
In a large bowl, toss the trimmed asparagus with olive oil, garlic powder, lemon zest, salt, and black pepper until evenly coated.
Place the asparagus directly on the grill grates and cook for about 5-7 minutes, turning occasionally, until tender and slightly charred.
Remove the asparagus from the grill and transfer to a serving platter.
Sprinkle the crumbled feta cheese over the grilled asparagus.
Drizzle with fresh lemon juice and garnish with chopped parsley if desired.
Serve immediately while warm.