This .NET class wraps the AcDbEntity ObjectARX class. It is the base class for all database objects having a graphical representation.

Autodesk.AutoCAD.DatabaseServices.DBObject
    Autodesk.AutoCAD.DatabaseServices.Entity
        Autodesk.AutoCAD.DatabaseServices.BlockBegin
        Autodesk.AutoCAD.DatabaseServices.BlockEnd
        Autodesk.AutoCAD.DatabaseServices.BlockReference
        Autodesk.AutoCAD.DatabaseServices.Body
        Autodesk.AutoCAD.DatabaseServices.Curve
        Autodesk.AutoCAD.DatabaseServices.DBPoint
        Autodesk.AutoCAD.DatabaseServices.DBText
        Autodesk.AutoCAD.DatabaseServices.DetailSymbol
        Autodesk.AutoCAD.DatabaseServices.Dimension
        Autodesk.AutoCAD.DatabaseServices.Face
        Autodesk.AutoCAD.DatabaseServices.FeatureControlFrame
        Autodesk.AutoCAD.DatabaseServices.GeoPositionMarker
        Autodesk.AutoCAD.DatabaseServices.Hatch
        Autodesk.AutoCAD.DatabaseServices.Image
        Autodesk.AutoCAD.DatabaseServices.Light
        Autodesk.AutoCAD.DatabaseServices.MLeader
        Autodesk.AutoCAD.DatabaseServices.Mline
        Autodesk.AutoCAD.DatabaseServices.MText
        Autodesk.AutoCAD.DatabaseServices.Ole2Frame
        Autodesk.AutoCAD.DatabaseServices.PointCloud
        Autodesk.AutoCAD.DatabaseServices.PointCloudEx
        Autodesk.AutoCAD.DatabaseServices.PolyFaceMesh
        Autodesk.AutoCAD.DatabaseServices.PolygonMesh
        Autodesk.AutoCAD.DatabaseServices.ProxyEntity
        Autodesk.AutoCAD.DatabaseServices.Region
        Autodesk.AutoCAD.DatabaseServices.Section
        Autodesk.AutoCAD.DatabaseServices.SectionSymbol
        Autodesk.AutoCAD.DatabaseServices.SequenceEnd
        Autodesk.AutoCAD.DatabaseServices.Shape
        Autodesk.AutoCAD.DatabaseServices.Solid
        Autodesk.AutoCAD.DatabaseServices.Solid3d
        Autodesk.AutoCAD.DatabaseServices.SubDMesh
        Autodesk.AutoCAD.DatabaseServices.Surface
        Autodesk.AutoCAD.DatabaseServices.UnderlayReference
        Autodesk.AutoCAD.DatabaseServices.Vertex
        Autodesk.AutoCAD.DatabaseServices.ViewBorder
        Autodesk.AutoCAD.DatabaseServices.Viewport

Public abstract Class Entity
Inherits DBObject

public abstract class Entity : DBObject;

RXObject