diff --git a/Sources/MockoloFramework/Models/ParsedEntity.swift b/Sources/MockoloFramework/Models/ParsedEntity.swift
index ba34e746..7cf10edf 100644
--- a/Sources/MockoloFramework/Models/ParsedEntity.swift
+++ b/Sources/MockoloFramework/Models/ParsedEntity.swift
@@ -87,6 +87,7 @@ struct ResolvedEntityContainer {
 protocol EntityNode {
     var namespaces: [String] { get }
     var nameText: String { get }
+    var mayHaveGlobalActor: Bool { get }
     var accessLevel: String { get }
     var attributesDescription: String { get }
     var declType: DeclType { get }
diff --git a/Sources/MockoloFramework/Operations/Generator.swift b/Sources/MockoloFramework/Operations/Generator.swift
index a035d3d9..e020c94c 100644
--- a/Sources/MockoloFramework/Operations/Generator.swift
+++ b/Sources/MockoloFramework/Operations/Generator.swift
@@ -107,12 +107,21 @@ public func generate(sourceDirs: [String],
     let t2 = CFAbsoluteTimeGetCurrent()
     log("Took", t2-t1, level: .verbose)
     
-    let typeKeyList = [parentMocks.compactMap {$0.key.components(separatedBy: "Mock").first}, annotatedProtocolMap.map {$0.key}].flatMap{$0}
-    var typeKeys = [String: String]()
-    typeKeyList.forEach { (t: String) in
-        typeKeys[t] = "\(t)Mock()"
-    }
-    SwiftType.customTypeMap = typeKeys
+    let typeKeyList = [
+        parentMocks.compactMap { (key, value) -> String? in
+            if value.entityNode.mayHaveGlobalActor {
+                return nil
+            }
+            return key.components(separatedBy: "Mock").first
+        },
+        annotatedProtocolMap.filter { !$0.value.entityNode.mayHaveGlobalActor }.map(\.key)
+    ]
+        .flatMap { $0 }
+        .map { typeName in
+            // nameOverride does not work correctly but it giving up.
+            return (typeName, "\(typeName)Mock()")
+        }
+    SwiftType.customDefaultValueMap = [String: String](typeKeyList, uniquingKeysWith: { $1 })
 
     signpost_begin(name: "Generate models")
     log("Resolve inheritance and generate unique entity models...", level: .info)
diff --git a/Sources/MockoloFramework/Parsers/SwiftSyntaxExtensions.swift b/Sources/MockoloFramework/Parsers/SwiftSyntaxExtensions.swift
index dacf2eb4..c3200af7 100644
--- a/Sources/MockoloFramework/Parsers/SwiftSyntaxExtensions.swift
+++ b/Sources/MockoloFramework/Parsers/SwiftSyntaxExtensions.swift
@@ -267,6 +267,10 @@ extension ProtocolDeclSyntax: EntityNode {
         return name.text
     }
 
+    var mayHaveGlobalActor: Bool {
+        return attributes.mayHaveGlobalActor
+    }
+
     var accessLevel: String {
         return self.modifiers.acl 
     }
@@ -313,6 +317,10 @@ extension ClassDeclSyntax: EntityNode {
         return name.text
     }
 
+    var mayHaveGlobalActor: Bool {
+        return attributes.mayHaveGlobalActor
+    }
+
     var accessLevel: String {
         return self.modifiers.acl 
     }
@@ -381,6 +389,25 @@ fileprivate func findNamespaces(parent: Syntax?) -> [String] {
         .reversed()
 }
 
+extension AttributeListSyntax {
+    fileprivate var mayHaveGlobalActor: Bool {
+        let wellKnownGlobalActor: Set<String> = [.mainActor]
+        return self.contains { element in
+            switch element {
+            case .attribute(let attribute):
+                return wellKnownGlobalActor.contains(attribute.attributeName.trimmedDescription)
+            case .ifConfigDecl(let ifConfig):
+                return ifConfig.clauses.contains { clause in
+                    if case .attributes(let attributes) = clause.elements {
+                        return attributes.mayHaveGlobalActor
+                    }
+                    return false
+                }
+            }
+        }
+    }
+}
+
 extension VariableDeclSyntax {
     func models(with acl: String, declType: DeclType, metadata: AnnotationMetadata?, processed: Bool) -> [Model] {
         // Detect whether it's static
diff --git a/Sources/MockoloFramework/Templates/ClosureTemplate.swift b/Sources/MockoloFramework/Templates/ClosureTemplate.swift
index 75e0ffcd..820e8152 100644
--- a/Sources/MockoloFramework/Templates/ClosureTemplate.swift
+++ b/Sources/MockoloFramework/Templates/ClosureTemplate.swift
@@ -64,15 +64,14 @@ extension ClosureModel {
     private func renderReturnDefaultStatement(name: String, type: SwiftType) -> String {
         guard !type.isUnknown else { return "" }
         
-        let result = type.defaultVal() ?? String.fatalError
-        
-        if result.isEmpty {
-            return ""
-        }
-        if result.contains(String.fatalError) {
-            return "\(String.fatalError)(\"\(name) returns can't have a default value thus its handler must be set\")"
+        if let result = type.defaultVal() {
+            if result.isEmpty {
+                return ""
+            }
+            return  "return \(result)"
         }
-        return  "return \(result)"
+
+        return "\(String.fatalError)(\"\(name) returns can't have a default value thus its handler must be set\")"
     }
 
     private func renderOptionalGenericClosure(
diff --git a/Sources/MockoloFramework/Utils/StringExtensions.swift b/Sources/MockoloFramework/Utils/StringExtensions.swift
index 31c2cd65..378ae29f 100644
--- a/Sources/MockoloFramework/Utils/StringExtensions.swift
+++ b/Sources/MockoloFramework/Utils/StringExtensions.swift
@@ -100,6 +100,7 @@ extension String {
     static let name = "name"
     static let sendable = "Sendable"
     static let uncheckedSendable = "@unchecked Sendable"
+    static let mainActor = "MainActor"
     static public let mockAnnotation = "@mockable"
     static public let mockObservable = "@MockObservable"
     static public let poundIf = "#if "
@@ -120,6 +121,15 @@ extension String {
         return self
     }
 
+    var removingExistentialAny: String {
+        var typeName = self
+        if typeName.hasPrefix(.any) {
+            typeName.removeFirst(String.any.count)
+            typeName = typeName.trimmingCharacters(in: .whitespaces)
+        }
+        return typeName
+    }
+
     var withSpace: String {
         return "\(self) "
     }
diff --git a/Sources/MockoloFramework/Utils/TypeParser.swift b/Sources/MockoloFramework/Utils/TypeParser.swift
index 60d102b1..61277529 100644
--- a/Sources/MockoloFramework/Utils/TypeParser.swift
+++ b/Sources/MockoloFramework/Utils/TypeParser.swift
@@ -343,7 +343,6 @@ public final class SwiftType {
     ///  if "non-nil", type is non-optional
     ///  if "", type is String, with an empty string value
     func defaultVal(with overrides: [String: String]? = nil, overrideKey: String = "", isInitParam: Bool = false) -> String? {
-
         if let val = cachedDefaultVal {
             return val
         }
@@ -364,7 +363,8 @@ public final class SwiftType {
             return cachedDefaultVal
         }
 
-        if let val = SwiftType.customTypeMap?[typeName] {
+        // There is no "existential any" to the customDefaultValueMap key.
+        if let val = SwiftType.customDefaultValueMap?[typeName.removingExistentialAny] {
             cachedDefaultVal = val
             return val
         }
@@ -466,7 +466,7 @@ public final class SwiftType {
             return "\(arg.typeName)()"
         }
 
-        if let val = SwiftType.defaultTypeValueMap[arg.typeName] {
+        if let val = SwiftType.defaultValueMap[arg.typeName] {
             return val
         }
         return nil
@@ -640,7 +640,7 @@ public final class SwiftType {
         }
     }
 
-    public static var customTypeMap: [String: String]?
+    public static var customDefaultValueMap: [String: String]?
 
     private let bracketPrefixTypes = ["Array", "Set", "Dictionary"]
     private let rxTypes = [String.publishSubject : "()",
@@ -656,7 +656,7 @@ public final class SwiftType {
     }
 
 
-    private static let defaultTypeValueMap =
+    private static let defaultValueMap =
         ["Int": "0",
          "Int8": "0",
          "Int16": "0",
@@ -676,6 +676,7 @@ public final class SwiftType {
          "TimeInterval": "0.0",
          "NSTimeInterval": "0.0",
          "PublishSubject": "PublishSubject()",
+         "Data": "Data()",
          "Date": "Date()",
          "NSDate": "NSDate()",
          "CGRect": ".zero",
@@ -685,14 +686,10 @@ public final class SwiftType {
          "UIColor": ".black",
          "UIFont": ".systemFont(ofSize: 12)",
          "UIImage": "UIImage()",
-         "UIView": "UIView(frame: .zero)",
-         "UIViewController": "UIViewController()",
-         "UICollectionView": "UICollectionView(frame: .zero, collectionViewLayout: UICollectionViewLayout())",
-         "UICollectionViewLayout": "UICollectionViewLayout()",
-         "UIScrollView": "UIScrollView()",
          "UIScrollViewKeyboardDismissMode": ".interactive",
          "UIAccessibilityTraits": ".none",
          "Void": "Void",
+         "()": "()",
          "URL": "URL(fileURLWithPath: \"\")",
          "NSURL": "NSURL(fileURLWithPath: \"\")",
          "UUID": "UUID()",
diff --git a/Tests/TestActor/ActorTests.swift b/Tests/TestActor/ActorTests.swift
index 7b223b7a..1691649d 100644
--- a/Tests/TestActor/ActorTests.swift
+++ b/Tests/TestActor/ActorTests.swift
@@ -8,4 +8,9 @@ final class ActorTests: MockoloTestCase {
         verify(srcContent: parentProtocolInheritsActor,
                dstContent: parentProtocolInheritsActorMock)
     }
+
+    func testGlobalActorProtocol() {
+        verify(srcContent: globalActorProtocol,
+               dstContent: globalActorProtocolMock)
+    }
 }
diff --git a/Tests/TestActor/FixtureGlobalActor.swift b/Tests/TestActor/FixtureGlobalActor.swift
new file mode 100644
index 00000000..40387ed2
--- /dev/null
+++ b/Tests/TestActor/FixtureGlobalActor.swift
@@ -0,0 +1,45 @@
+import MockoloFramework
+
+let globalActorProtocol = """
+/// \(String.mockAnnotation)
+@MainActor protocol RootController: AnyObject {
+    var viewController: UIViewController { get }
+}
+
+/// \(String.mockAnnotation)
+protocol RootBuildable {
+    func build() -> RootController
+}
+"""
+
+let globalActorProtocolMock = """
+class RootControllerMock: RootController {
+    init() { }
+    init(viewController: UIViewController) {
+        self._viewController = viewController
+    }
+
+
+
+    private var _viewController: UIViewController! 
+    var viewController: UIViewController {
+        get { return _viewController }
+        set { _viewController = newValue }
+    }
+}
+
+class RootBuildableMock: RootBuildable {
+    init() { }
+
+
+    private(set) var buildCallCount = 0
+    var buildHandler: (()  -> (RootController))?
+    func build()  -> RootController {
+        buildCallCount += 1
+        if let buildHandler = buildHandler {
+            return buildHandler()
+        }
+        fatalError("buildHandler returns can't have a default value thus its handler must be set")
+    }
+}
+"""
diff --git a/Tests/TestExistentialAny/ExistentialAnyTests.swift b/Tests/TestExistentialAny/ExistentialAnyTests.swift
index f0f5bf7e..6e4839c7 100644
--- a/Tests/TestExistentialAny/ExistentialAnyTests.swift
+++ b/Tests/TestExistentialAny/ExistentialAnyTests.swift
@@ -5,4 +5,9 @@ class ExistentialAnyTests: MockoloTestCase {
         verify(srcContent: existentialAny,
                dstContent: existentialAnyMock)
     }
+
+    func testExistentialAnyDefaultTypeMap() {
+        verify(srcContent: existentialAnyDefaultTypeMap,
+               dstContent: existentialAnyDefaultTypeMapMock)
+    }
 }
diff --git a/Tests/TestExistentialAny/FixtureExistentialAny.swift b/Tests/TestExistentialAny/FixtureExistentialAny.swift
index be40c1f5..2bbaeeb4 100644
--- a/Tests/TestExistentialAny/FixtureExistentialAny.swift
+++ b/Tests/TestExistentialAny/FixtureExistentialAny.swift
@@ -45,3 +45,37 @@ class ExistentialAnyMock: ExistentialAny {
     }
 }
 """
+
+let existentialAnyDefaultTypeMap = """
+/// \(String.mockAnnotation)
+protocol SomeProtocol {
+}
+
+/// \(String.mockAnnotation)
+protocol UseSomeProtocol {
+    func foo() -> any SomeProtocol
+}
+"""
+
+let existentialAnyDefaultTypeMapMock = """
+class SomeProtocolMock: SomeProtocol {
+    init() { }
+
+
+}
+
+class UseSomeProtocolMock: UseSomeProtocol {
+    init() { }
+
+
+    private(set) var fooCallCount = 0
+    var fooHandler: (()  -> (any SomeProtocol))?
+    func foo()  -> any SomeProtocol {
+        fooCallCount += 1
+        if let fooHandler = fooHandler {
+            return fooHandler()
+        }
+        return SomeProtocolMock() 
+    }
+}
+"""