Preheat oven to 400°F and place rack in the middle position.
In a large bowl, combine eggplant, zucchinis, red and yellow bell peppers, and red onion.
Add olive oil, oregano, thyme, rosemary, salt, and pepper to the vegetables and toss until evenly coated.
Spread the seasoned vegetables in a single layer on a large rimmed baking sheet, leaving space between pieces for even roasting.
Roast for 20 minutes, then remove and gently stir or flip the vegetables.
Add cherry tomatoes and minced garlic to the baking sheet and mix with other vegetables.
Return to the oven and roast for an additional 10-12 minutes until vegetables are tender and lightly caramelized at the edges.
Remove from oven and immediately drizzle with lemon juice; add Kalamata olives if using and toss gently.
Transfer to a serving platter and sprinkle with crumbled feta cheese and chopped parsley.
Serve warm or at room temperature.